Friday, June 24, 2005

MAN DID REACH THE MOON!

Dear all,
 
Before the explanation, here are some useful links.
 
 
 
Now, here are the opposing explanations to all the reasons that claimed that "Man didn't land on the moon".
 
 [REST ASSURED, MAN DID LAND ON MOON!]

What is the evidence?

1) Claim: Film clearly shows a flapping flag but there is no wind on the moon, how can this be?

Argument: It isn't flapping, things can move in a vacuum, it's just 'wobbling' until it finds its center of gravity which, in weightless space, is everywhere.

2) Claim: There are various lighting discrepancies on pictures which indicate more than one light source, when the only light source was the Sun, there was no artificial light source taken.

Argument: If there are two light sources on the pictures used for this evidence, then why aren't there two shadows? Check out the perspective which could compromise the pictures.

3) Claim: There are no stars in the sky

Argument: They are there, you just can't see them. In daytime on earth the stars are still there, you just can't see them.

4) Claim: There is no engine noise behind the voice of the astronaut as it comes down to land on the moon. The sound of the engines should have been deafening.

Argument: The microphone is at the mouth of the astronaut. In space there is no sound, thus you couldn't hear the engine noise.

5) Claim: There is no blast crater beneath the lunar lander

Argument: They decelerated down slowly, they didn't crash down, they were slow enough to cause dust clouds but not remove all dust.

6) Claim: There are pictures of the feet of the lunar lander which look completely dust free, why?

Argument: There is no moisture in space, nothing for dust to cling to and thus it just did not stick, hence it looks pristine.

7) Claim: The on-moon photographs were taken with cameras which had view finders on which the astronauts could not see, yet a number of the pictures are perfectly framed.

Argument: OK so they couldn't see the view finder, but they practiced endlessly on earth before they went. They took thousands of pictures and only showed the good ones.

8) Claim: The space suits and the space craft were just not strong enough to fight off the radiation either on the Moon itself or through the Van Allen radiation belt.

Argument: They went through the Van Allen belt in an hour, this was not enough time to be affected by the radiation. The astronauts were affected by radiation, they just were not made ill by it as the doses were small. As for 'how did they survive the sun's radiation on the moon if the suits weren't strong enough': Hmmm... well, the suits must have been strong enough if you think the conspiracy is wrong, or they didn't go...

9) Claim: The moon walking, if doubled in speed, looks like running on earth.

Argument: UHM, NOT REALLY. OK if they had a suspension cord on their backs maybe, but take a look at the moony buggy, that looks realistic driving in a weightless environment.

10) Claim: There were problems on earth with the LAM moon lander, which was very unstable on earth (if you moved your body weight slightly it would destabilize the craft, but on the moon pictures it was flawless.

Argument: You are in weightlessness up there, the problems were all because of gravity on the earth.

11) Claim: Photos: When an astronaut goes into the shadows you can still see him, why, there is no light? Also there is at least one picture with the sun behind the craft but everything in the foreground is clearly visible, with no secondary light source surely this is not possible, it should have been in a shadow.

Argument: Yes but light bounces off objects too so that doesn't prove anything - the sun's light could bounce off the surface of the moon (even on earth the sun lights things it doesn't have a direct line of sight of.)

12) Claim: On some of the film footage from the moon there seems to be identical scenery, one with the lander on, one without. Clearly the one without must be wrong as they had not been there before and after they left the lander base was still there.

Argument: But there are differences, the backgrounds are not identical if you look closely enough. The Moon is a pretty featureless place and certain mountains can look similar.

13) Claim: Identical backgrounds on different days with pictures of astronauts looking around but we are told this is a different day, how can this be?

Argument: It's a simple mistake.

14) Claim: People have been killed and threatened to keep this story quiet.

Argument: 750,000 people work either directly or indirectly for NASA - they couldn't keep this a secret.

15) Claim: Launch of Apollo 11 did happen, just the astronauts went round the earth for 8 days, in the interim NASA showed the pictures and then they touched down again.

Argument: There is testimony from very respected astronauts who say they went to the moon, are they liars?

16) Claim: Strange camera work on Apollo movies which suggest a person is working the camera when in fact nobody could possibly have been left on the moon to operate the camera.

This starting frame shows the camera looking straight at the Apollo craft as it blasts off from the moon's surface.
As it goes up, the camera pans upwards.
Even higher... the camera filming this (on the moon) continues to follow the ship upwards (see the scenery at the bottom of the screen disappear). But there was nobody left on the moon to film this, surely this is further evidence this is all a fraud?

(If you look at the video [see below] you can also see that the camera seems to pull backwards slightly when the explosion takes place, as if someone is pulling back... All very strange...)

Argument: No person was working the camera, the automatic camera could focus on an object and was programmed to follow it, (or maybe it could be controlled from ground control.)

Later on in this particular movie:

In this picture the space ship (which blasted off in the sequence above) is shown floating above the moon's surface. But there must be a camera above it to take this shot! Was there a second space ship filming this? Or is the whole thing a fake, or somehow computer generated?

Argument: There was a second ship from which this was filmed. This smaller ship on the picture couldn't have made it back to Earth on its own. It had to dock with a mother ship ie the ship with the camera on it filming this shot.

 
 


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Thursday, June 23, 2005

List of country based domains

 
Different countries of the world and with their own coutry domains
(for ex, .in for India as in www.yahoo.co.in)
 
 
 
Code    Country              [sorted alphabetically]
----------------------
 
AC   Ascension Island            
AD   Andorra                                             
AE   United Arab Emirates       
AF   Afghanistan(Islamic St.)   
AG   Antigua and Barbuda         
AI   Anguilla                   
AL   Albania                    
AM   Armenia                        
AN   Netherland Antilles        
AO   Angola (Republic of)       
AQ   Antarctica                     
AR   Argentina                  
AS   American Samoa             
AT   Austria                    
AU   Australia                  
AW  Aruba                      
AZ   Azerbaidjan                    
BA   Bosnia-Herzegovina         
BB   Barbados                   
BD   Bangladesh                 
BE   Belgium                    
BF   Burkina Faso               
BG   Bulgaria                   
BH   Bahrain                    
BI    Burundi                    
BJ    Benin                      
BM   Bermuda                    
BN   Brunei Darussalam          
BO   Bolivia                    
BR   Brazil                     
BS   Bahamas                    
BT   Bhutan                      
BV   Bouvet Island
BW   Botswana                   
BY   Belarus                    
BZ   Belize                      
CA   Canada                  
CC   Cocos (Keeling) Isl.        
CD   Rep. Dem. Congo     
CF   Central African Rep.       
CG   Congo                       
CH   Switzerland                
CI    Ivory Coast                
CK   Cook Islands               
CL   Chile                    
CM   Cameroon                   
CN   China                      
CO   Colombia                     
CR   Costa Rica                  
CU   Cuba                       
CV   Cape Verde                 
CX   Christmas Island             
CY   Cyprus                     
CZ   Czech Republic             
DE   Germany                    
DJ    Djibouti                   
DK   Denmark                    
DM   Dominica                   
DO   Dominican Republic         
DZ   Algeria                    
EC   Ecuador                    
EE   Estonia                    
EG   Egypt                      
EH   Western Sahara
ER   Eritrea                    
ES   Spain                      
ET   Ethiopia                   
FI   Finland                  
FJ   Fiji                       
FK   Falkland Isl.(Malvinas)     
FM   Micronesia                 
FO   Faroe Islands              
FR   France                     
GA   Gabon                      
GB   Great Britain (UK)           
GD   Grenada                    
GE   Georgia                        
GF   Guiana (Fr.)               
GG   Guernsey  (Ch. Isl.)       
GH   Ghana                      
GI   Gibraltar                   
GL   Greenland                  
GM   Gambia                     
GN   Guinea                     
GP   Guadeloupe (Fr.)           
GQ   Equatorial Guinea          
GR   Greece                     
GS   South Georgia and South Sandwich Islands    
GT   Guatemala                  
GU   Guam (US)                  
GW   Guinea Bissau              
GY   Guyana                     
HK   Hong Kong                  
HM   Heard & McDonald Isl.      
HN   Honduras                    
HR   Croatia                    
HT   Haiti                      
HU   Hungary                    
ID   Indonesia                  
IE   Ireland                    
IL   Israel                     
IM   Isle of Man                
IN   India                      
IO   British Indian O. Ter.     
IQ   Iraq                       
IR   Iran                       
IS   Iceland                  
IT   Italy                    
JE   Jersey (Ch. Isl.)          
JM   Jamaica                    
JO   Jordan                     
JP   Japan                      
KE   Kenya                      
KG   Kyrgyz Republic                  
KH   Cambodia                   
KI   Kiribati                    
KM   Comoros                    
KN   St.Kitts Nevis Ang. 
KP   Korea (North)                                 
KR   Korea (South)              
KW   Kuwait                         
KY   Cayman Islands             
KZ   Kazakstan                      
LA   Laos                       
LB   Lebanon                    
LC   Saint Lucia                
LI   Liechtenstein              
LK   Sri Lanka                  
LR   Liberia                    
LS   Lesotho                    
LT   Lithuania                       
LU   Luxembourg                 
LV   Latvia                         
LY   Libya                
MA   Morocco                      
MC   Monaco                     
MD   Moldova                       
MG   Madagascar                 
MH   Marshall Islands             
MK   Macedonia (former Yug.)    
ML   Mali                       
MM   Myanmar                     
MN   Mongolia                   
MO   Macau                      
MP   Northern Mariana Isl.      
MQ   Martinique (Fr.)           
MR   Mauritania                 
MS   Montserrat                   
MT   Malta                      
MU   Mauritius                   
MV   Maldives                   
MW   Malawi                     
MX   Mexico                     
MY   Malaysia                   
MZ   Mozambique                 
NA   Namibia                    
NC   New Caledonia (Fr.)        
NE   Niger                       
NF   Norfolk Island             
NG   Nigeria                    
NI   Nicaragua                  
NL   Netherlands                
NO   Norway                  
NP   Nepal                      
NR   Nauru
NU   Niue                       
NZ   New Zealand                
OM   Oman                       
PA   Panama                      
PE   Peru                       
PF   Polynesia (Fr.)            
PG   Papua New Guinea           
PH   Philippines                
PK   Pakistan                   
PL   Poland                     
PM   St. Pierre & Miquelon        
PN   Pitcairn                     
PR   Puerto Rico (US)          
PS   Palestinian Terr, Occ.     
PT   Portugal                   
PW   Palau                      
PY   Paraguay                   
QA   Qatar                      
RE   Reunion (Fr.)                
RO   Romania                    
RU   Russian Federation             
RW   Rwanda                     
SA   Saudi Arabia               
SB   Solomon Islands            
SC   Seychelles                 
SD   Sudan                      
SE   Sweden
SG   Singapore                  
SH   St. Helena
SI   Slovenia                   
SJ   Svalbard & Jan Mayen Is         
SK   Slovakia (Slovak Rep)      
SL   Sierra Leone               
SM   San Marino                 
SN   Senegal                    
SO   Somalia                    
SR   Suriname                   
ST   St. Tome and Principe       
SU   Soviet Union                   
SV   El Salvador                
SY   Syria                      
SZ   Swaziland                  
TC   Turks & Caicos Islands     
TD   Chad                       
TF   French Southern Terr.        
TG   Togo                       
TH   Thailand                       
TJ   Tadjikistan                         
TK   Tokelau     
TM   Turkmenistan                   
TN   Tunisia                    
TO   Tonga                      
TP   East Timor                  
TR   Turkey                     
TT   Trinidad & Tobago          
TV   Tuvalu                      
TW   Taiwan                      
TZ   Tanzania                   
UA   Ukraine                    
UG   Uganda                     
UK   United Kingdom                  
UM   US Minor outlying Isl.
US   United States                  
UY   Uruguay                    
UZ   Uzbekistan                     
VA   Vatican City State         
VC   St.Vincent & Grenadines    
VE   Venezuela                  
VG   Virgin Islands (Brit)      
VI   Virgin Islands (US)        
VN   Vietnam                    
VU   Vanuatu                    
WF   Wallis & Futuna Islands
WS   Western Samoa               
YE   Yemen                      
YT   Mayotte
YU   Yugoslavia                        
ZA   South Africa               
ZM   Zambia                         
ZW   Zimbabwe                       

 


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Friday, June 17, 2005

So what is 64-bit?

It's the 64-bit question ...

Chris Green explains what the technology has to offer PC users - today and in the future.

Chris Green, Computing 15 Mar 2004
 

64-bit is the next generation of PC processor technology. Unless the PC on your desk is pre-Windows 95 (unlikely), it has a 32-bit processor. If it's very new, that chip will be a Pentium 4 or an Athlon XP.

64-bit chips are the next stage, delivering even more processing power and new technologies to improve graphics performance and web surfing.

How did we get to 64-bit?
The original x86 processor had eight-bit internal data pathways, so it could process eight bits (or instructions) at a time. The next development, the 386, was called a 16-bit processor because its internal data pathways were 16-bit, and so on.

The past 26 years have seen us move gradually through various developments in PC technology. The PC as we know it was born in 1978 when Intel released the 8086, an eight-bit processor that was used in the original IBM PC.

Intel went 16-bit in 1985 with the 386 and 32-bit in 1989 with the 486-DX. The original Pentium was also 32-bit.

The next evolution is 64-bit, which is capable of handling twice as many instructions again at a time, and capable of transporting those instructions through the pathways at a phenomenal rate.

OK. But processor technology gets faster all the time. So what?
This is a bit more significant than the usual round of slightly faster chips. 64-bit represents a move to a completely new hardware technology, one that eliminates many of the performance bottlenecks of current 32-bit technology.

The evolution from eight-bit to 16-bit, and particularly from 16-bit to 32-bit, saw the newer incarnations of the chips being saddled with a lot of legacy baggage to ensure compatibility with legacy software.

The move from the current 32-bit chips to 64-bit will deliver a major leap in performance, because legacy support is either being dropped completely or is ring-fenced within the processor.

This means that the 64-bit capability is not hampered by slower, more inefficient 32-bit instruction sets and data handling. Instead, 64-bit chips are free to use new hardware technology that can be exploited by future software and operating systems.

You said future?
As is always the case with these things, the hardware is out before the software that will take advantage of it. But software is playing catch-up. Microsoft is planning to release a 64-bit version of Windows XP this summer.

There are also several builds of 64-bit Linux in the offing, including a version from Mandrake that is optimised for AMD's 64-bit platforms.

And I suppose I'll need to replace most of the guts of a machine if I upgrade it?
The 64-bit chips have different pin arrangements and power requirements than even the latest Athlon XP and Pentium 4 processors, and they rely on completely new motherboard chipsets.

So in short, if you are looking to upgrade a machine in situ, you'll need a new processor and a new motherboard at the very minimum. You'll almost certainly need some new memory as well.

Who's making these chips?
The usual suspects: AMD and Intel. Interestingly, AMD is very much running the show this time round. It has beaten Intel to market with a 64-bit desktop processor by six months. Intel didn't even announce plans to add 64-bit extensions to existing 32-bit chips until February this year.

But wasn't there already a 64-bit Alpha processor?
Yes, the Alpha server and workstation processor developed by DEC was indeed 64-bit. Sadly, when DEC was acquired by Compaq, development of the Alpha was quietly dropped, and the technology has begun to fade from active use and support. For example, Microsoft dropped OS support for it after NT4.

However, the Alpha continues to have a role to play in 64-bit computing. AMD licensed part of the Alpha bus technology for use in the Athlon XP, and hired many members of the Alpha development team.

This knowledge has carried forward into AMD's Athlon64 and Opteron, while Intel eventually acquired the technology from Compaq in late 2001.

So which 64-bit chips are available now?
AMD has two 64-bit processors: Athlon64 for desktop PCs and laptops, and Opteron for servers.

Both of these are fully backwards-compatible with existing 32-bit software and peripherals. Intel's 64-bit server platform Itanium, however, is not backwards-compatible, although its 64-bit extended chips will be.

So even though there is no 64-bit software out there, can I still use a 64-bit PC?
Yes. You can buy 64-bit hardware now, and use your existing software on it. 64-bit PCs will even run 32-bit software with a decent performance gain.

As and when 64-bit operating systems and applications come on the market, you will already have the infrastructure in place to run them.

OK, so how much is a 64-bit PC going to cost me?
Not as much as you might think. Retailers such as PC World are selling high-spec AMD-based 64-bit PCs in the £1,000-1,500 price range, and IBM is shipping Opteron-based servers starting at £2,000 for a single-processor machine. HP and Sun are also due to launch Opteron products this year.

In the light of recent comments by Michael Dell, there is even a possibility that Dell might break with its traditional Intel-only stance and release a range of AMD 64-bit based servers.

As for Intel, Itanium 2 processors are almost exclusively used in supercomputer applications at the moment, making it difficult to put an everyday price on them. However, 64-bit extended desktop processors should start appearing in the second half of this year.

32-BIT 'COMPUTERS ON A CHIP'

Missing from this picture is Cyrix, a little-known brand that was once independent, has since been owned by National Semiconductor, and now belongs to chipset maker VIA.

Like AMD, Cyrix produced x86-compatible processors under licence from Intel during the years of the 80286 and 80386. Cyrix then decided to make its own processors and created the Cyrix 486.

Again like AMD, it continued to produce its self-engineered x86 compatible processors, but ran behind Intel in terms of getting comparable products to market at the same time.

In 1997, Cyrix released its most successful x86 clone, the 6x86MX - a rival to Intel's Pentium MMX. Cyrix licensed the MMX extensions from Intel for use in the chip. This, along with AMD's K6 and later the K6-2 processors, competed with Intel at the lower end of the market.

In 1999, Cyrix was sold to VIA and has since conceded the mainstream market to AMD and Intel. Instead, Cyrix is focusing on so-called 'computer on a chip' 32-bit products.

The Cyrix MediaGX processor, for example, is used extensively in set-top boxes and embedded devices. VIA also uses Cyrix processor technology in complete chipsets for ultra-small ITX PC motherboards, which are popular with computer gamers, Linux users and individuals looking for very small, low-noise and low-power x86-compatible PCs.

www.amd.com/opteron
www.intel.com/itanium

 

Source:

http://www.computeractive.co.uk/computing/features/2072385/bit-question



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New system integrates landlines and cellphones

New system integrates landlines and cellphones

The world’s first combined phone service, which allows a single handset to switch between cellphone networks and domestic fixed-lines, was launched by BT in the UK on Wednesday.

Called BT Fusion, the service means a handset works like a typical cellphone when outdoors, but automatically and seamlessly switches onto a user’s domestic account when they are home - even in mid-call.

To achieve this, the phone uses a Bluetooth wireless connection to relay the call to a broadband hub in the home. This hub can also be used as a wireless router for home computer Wi-Fi networks.

According to BT, the benefits to customers - besides having a combined landline and cellphone bill - is that calls made at home will be priced at domestic rates and with the same quality of a fixed line.

Making house calls

Another feature of the new service is that it will allow customers to switch to their domestic account when at someone else’s house, a BT spokesman told New Scientist. The cost of the call will be charged back to their own account but they will benefit from domestic rates even though they are away from home, he says.

But this will only be possible if the house they are in subscribes to the same service and has given permission for the hub to be used, by way of an access code.

Some homeowners could face problems, however, because Bluetooth signals are relatively weak, the spokesman concedes. If a user’s home is particularly large, or spread over several floors, then they may end up using the cellphone network more often than desirable because the hub’s signal is too weak. But he adds: “In a fairly typical home there should be no problem.”

Risk of confusion

“I think having a single handset is the way forward, or at least being reachable at one contact point,” says Nico MacDonald, a design and technology strategist with the London-based consultancy Spy. But it has to be clear to the customer which network they are using, he says, and there is a danger that billing could become even less intelligible than current phone bills.

Initially the service will only be available to 400 households which will test it before its national launch in the UK in September 2005.

But by this time BT may have some competition. According to cell network provider Orange, it has been working with France Telecom to develop a similar service which will also be launched towards the end of 2005, but will include added features such as video calling between landlines and cellphones.

 

Source:

http://www.newscientist.com/article.ns?id=dn7526



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Wednesday, June 15, 2005

Shutting Down the Highway to Internet Hell



Larry Seltzer  
Shutting Down the Highway to Internet Hell
By Larry Seltzer


Opinion: The time has not only come for ISPs to block port 25 for consumer accounts, it has long since passed. The rewards for this and other ISP management techniques could be large, but ISPs need to be careful about how they do it and tell users why.


Do you run a mail server on your home Internet account? If you do, it's probably without your knowledge, such as in a mail worm or a zombie spambot. Few if any people running these programs intend to do so, and it's time for ISPs to close the door through which they operate.

I think there's a consensus developing among anti-spam researchers, many of them responsible for fighting spam on ISP networks, that unrestricted use of TCP port 25 must be shut down to the average Internet consumer. There are those who disagree, but their arguments sound obtuse and defeatist rather than actual justifications to not block port 25.

TCP Port 25 is one of the core interfaces of the Internet, through which Internet mail servers typically send mail to each other. It's normal for users to send data out port 25, but they do so to their own ISP's mail server, from which it is forwarded on to the appropriate location. This is the server identified as the outgoing mail server in the mail client configuration.

But if you are infected with a spam zombie—typically, a mail worm with a backdoor used by a spammer to cause your computer to send out massive amounts of spam—the mail does not go through your mail server. It probably goes directly to the server of the target domain for the spam message. The overwhelming majority of users have no need to do this and are perfectly well-served by sending all their mail through the ISP mail servers. It's also worth reiterating that the block need only be put on consumer client systems, not on higher-end services.

Of course there are users who do need access to the port, or who at least want to run their own mail server and don't intend to abuse the privilege. Or they have a need to use a different mail server than the ISPs, perhaps for reasons involving confidentiality. There are ways for ISPs to accommodate these users.

In fact, there's no reason an ISP can't make exceptions for users who want to use port 25 more openly, especially if they agree to rate limits and to configure it securely. The real problem that needs to be solved is the users who don't know they are running a mail server. Such users won't miss not being able to run one.

Alas, this level of customer service may be too much to expect from some ISPs. Hosting servers are also often far too lax in the management of mail on their networks.

ISPs Fighting Back

But some ISPs are putting their feet down, attempting to stop the abuse. At the forefront of this effort, defying all conventional wisdom, is AOL. In the 90s, an era of very different circumstances, AOL was the single largest source of spam on the Internet, and the ISP's reputation suffered terribly from it. Now not only AOL users have high-quality spam control, but AOL is perhaps the most active ISP in terms of policing the use and abuse of mail.

Consider the rules at AOL's "Technical Standards for E-mail Delivery." AOL makes extensive use of RBL services like MAPS so that they know to block spam from open relays, spambots, systems with unsecured form-mail scripts and other spam sources. They actually use the same services to block spam that comes directly from residential ISP clients that should not be sending mail directly; in other words, if you don't block port 25 yourself, they will do it for you.

The ISP goes further—much further. If the sending system does not have a PTR record (a reverse DNS), it is rejected. If a message contains a hex-encoded URL (like http://%73%70%61%6d/), it is rejected. If more than 10 percent of the sending system's messages to AOL bounce, AOL may reject mail from it in general. If a server rejects 10 percent or more of the bounce messages sent to it, AOL may reject further connections from the server. There are other, similar rules.

All of this is intended to use AOL's size and clout to make other e-mail administrators set up and administer their systems properly. In many cases, the reverse DNS requirement, for example, the administrator finds out that he or she doesn't have a reverse DNS because AOL blocks the mail, and the end result is an improvement for everyone. Mail servers should have a reverse DNS if they have nothing to hide.

Perhaps not everyone can do everything AOL does. It does, after all, have a proprietary internal mail system. But there's a lot we can learn from its example. Carl Hutzler, until recently in charge of AOL's anti-spam efforts (he has now moved on to a position in engineering and development of AOL's e-mail), has been evangelizing this ethic of responsibility by mail admins, especially at ISPs.

Hutzler warns of the lazy approach of relying on filters, as so many ISPs do. It's the easy way out. But anyone with a little experience knows that filters don't even come close to solving the problem, although they can be a useful part of the solution. I've seen messages with overtly pornographic subject lines and bodies make it through three different Bayesian filters. Spammers know how to play with the content of the message to trick filters.

Port 25, The Nuclear Option

But the technique that generates the most controversy is when an ISP blocks port 25, as SBC recently began to do.

As one prominent researcher put it, blocking port 25 begins the process of shifting the cost burden for spam from the end user to the ISP and others whose sloppiness in administration is responsible for the unchecked proliferation of spam, and these same people are in a position, through responsible system administration, to choke off most of the abuse. He also argued that the cost benefits of fixing their systems are enough incentive to do it.

The depressing counterargument is that many of these systems have excess capacity enough to handle the abuse and that laziness is its own reward. When this is the case, there's no choice but for other ISPs to start blocking the offending ISP, as AOL has done many a time.

This is another point on which a consensus is emerging: that ISPs don't take action to stop spammers on their networks until there is a gun to their heads, generally in the sense that their customers are prevented from sending mail. This is where the major RBLs like Spamhaus and MAPS can play a big role. They have a bad reputation among some, and I've personally been among the collateral damage from an RBL block. But it was my hosting service's fault that my server got on the block because they didn't do anything about the spammer on the same address that I had. Enough of us called and screamed, and something was done about it.

Not every little domain has the clout to block a major ISP. The little guy ends up hurting and angering his customers, but the big ISP won't even notice. But when one major ISP, or a service like MAPS, blocks a major ISP, it gets their attention. The corollary to this is that when you block someone, you need to be responsive when they fix the problem.

The fact that ISPs have no reason to not let users opt out of the system is what cinches it for me. One researcher suggested to me that it was much easier for ISPs just to block a whole range of addresses than to have to put up a system for tracking who was to be blocked and who shouldn't, but this is basically just arguing laziness as an excuse. Besides, the SBC system supports letting users request an opt-out. Why can SBC do it and others can't?

The same researcher was concerned that the opt-out system would be taken over by spammers who would opt-out their zombie systems. But it's not hard to imagine well-designed authentication systems that mail back a message to the customer and require them to connect back.

And as for the added cost to the ISP for this, I'd suggest that they might just save a lot of money by eliminating spammers and mail worms from their networks, but even if you think this is a costly solution, let them charge for the opt-out. Doesn't bother me.

Port 25, The Counterarguments

Those who argue against ISPs blocking port 25 generally claim that the downsides are high and that spammers will a) evade the blocks and b) easily move to other techniques for sending spam. Joe St. Sauver has made a well-written case for this position. I admire some of his points, but I still disagree with him, and I think half his problem is that he can't see the point through all his defeatism. Namely, even if spammers were to move to other avenues, it's still worth closing port 25 to stop them from using it.

Getting right to what I feel is the main point, that port 25 blocks will be ineffective because spammers will move to other methods to spread spam, St Sauver brushes aside or ignores counterarguments. He cites recent stories that spammers are beginning to use the ISP mail server instead of sending out spam directly from the client system. There are two counterarguments.

If the ISP requires SMTP AUTH (where you must provide a username and password for the outgoing SMTP mail server as well as the incoming POP3 server), then it will not be a simple matter for the worm to send mail. However, since there are programs available that can read the cached SMTP AUTH credentials from popular mail client programs (click here for one that's sold commercially), it's not hard to see spam zombies doing the same in the future. They might also do it by monitoring port 25 usage to look for the authentication sequence.

In fact, my own ISP, Speakeasy.net, is very lenient about these things. Speakeasy does not require SMTP AUTH for connections made on their internal network (it does for roaming users), but it says that it monitors mail servers carefully and maintains a number of honeypots on active lookout for malware on its networks.

I spoke to Speakeasy founder and Chairman Michael Apgar, and he insists that a system exhibiting wormlike behavior will not live for long on Speakeasy's network. Within hours the user will be contacted, and if he or she doesn't fix the problem quickly, the plug will be pulled. But Speakeasy is not a conventional ISP; while it's happy to sell to anyone, it has a technically more capable audience who pay more for more open services.

Apgar is quick to agree that mainstream consumer ISPs should be locking down abusable services, and that port 25 is the biggest problem.

Force the Spammers Onto Official Servers

Even if the zombie successfully is able to send spam through the ISP mail server, we're still better off than before. The ISP can tell, just by looking at mail server logs, who is spamming from its network. ISPs have a cost interest in fixing the situation and arguably are more responsible for doing so since their own servers were involved. Put simply, forcing the spammer onto the ISP mail server facilitates the elimination of zombies. It also gives the ISP the opportunity to rate-limit mail in general, which will not likely affect regular users, but will seriously cut into spammers' ability to spread the message.

I have a similar reaction to St. Sauver's speculation that zombies, blocked in their ability to send spam, will instead be used for even worse things like denial-of-service attacks. This is not hard to imagine, but while much of the world puts up with systems sending spam, they would feel different about a DOS army. And I can't see that the market for DOS armies scales in the same way that the spam market does. It's just not as big a threat.

He also points out that spammers could still evade blocks on port 25 at the network periphery by spamming inside the network—e.g., to other customers of the same ISP on their subnet. Of course, they will only be able to do so if the recipient mail server is on the same subnet, and this is highly unlikely on a large consumer ISP network.

While most of his writing is laboriously pessimistic, St. Sauver does have interesting constructive criticism. He urges those who would fight spam to focus not on the spam leaving the network but on the traffic coming in to the spambot. He asserts (this is counter to my understanding) that spambots don't typically construct the e-mails they send out programmatically but pass on what they receive from the outside. Whether this is true or not is beside the valid point he makes that it should be possible to look for the command/control coming into the network from spammers. While these commands come in on nonstandard ports, they are known (they have to be, or spammers couldn't find them either).

Finally, for all their claims that easy alternatives exist to port 25, they haven't come up with any. The first port usually listed is TCP 587, but like many of the potential alternatives, it's an authenticated port, so it's not blindly open for spamming use.

In the end, the biggest factor in whether ISPs will play hardball with spammers is whether they want to have to go to the problem of taking out the garbage and keeping their place clean. Some ISPs have complained to me about others who don't seem to care if their networks are used to send out billions of spam messages and mail worms. They don't even look at their own log files!

But the day is coming when these ISPs won't be able to coast through their own laziness and sloppiness. The use of RBLs like MAPS and other blocks of known spammer systems is an increasingly important technique, and if worms really do move to using the ISP mail server, then ISPs who don't do anything about it will find themselves blocked completely by the clean ISPs that are sick and tired of taking abuse.

I don't expect everyone to clean up their act, but think we're moving to an era of unofficial quality standards, of black and white lists, where ISPs will "protect" their customers from the red-light districts of the Internet. It's not perfect, but it's better than what we've got now.

Security Center Editor Larry Seltzer has worked in and written about the computer industry since 1983.

Source:

http://www.eweek.com/article2/0,1759,1784276,00.asp



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Tuesday, June 14, 2005

Mastering the Windows Task Manager

 Mastering the Windows Task Manager 
Date: March 3, 2004
By: Paul Corchado
 
 

I think that everyone who has used Windows XP would say it’s the most robust and most stable of all the Windows operating systems before it. However, there are times where an application or even a game doesn’t respond well or locks up the system. A lot of people would assume solutions from past operating system experience and just turn off the power and restart the computer. This technique is a little extreme and sometimes a little dangerous as well. Windows since version 98 has had a function called Task Manager, and with every version of Windows it’s gotten more powerful and better at bringing back locked up or misbehaving applications.

In the Task Managers before Windows 2000, holding the Ctrl-Alt-Del combination does either a complete reset of the system or brings up the task manager and hopefully allows you to shut down the program that is not responding; sometimes holding the keys doesn’t result in anything at all. Windows 9x or ME sometimes also evoked a blue screen of death if the Ctrl-Alt-Del was used. In Windows 9x, when you did get the task manager open and try to close a program that is not responding, sometimes it wouldn’t shut the application down, and you would still have to do a hard reset. I think Microsoft learned from Windows NT—which by far, up to this point, was better at handling locked up systems—and decided that the home PC user would appreciate the added stability especially when it came to installing beta software, hardware drivers, or even just tweaking one’s system and the software provided some unexpected results. Its important to have control when it is needed most, and that’s exactly what Windows NT-, 2000-, and XP-based operating systems gave the user.

XP’s Task Manager is the most useful of all managers before it. Just right-clicking on the task bar brings up a small menu, and through that menu one can select the Task Manager. The manager has several tabs running across the top, but the most important ones are the Applications, Processes, and Performance. Each one of these tabs will give users critical information regarding the status and health of their machines.

The Applications Tab

The Applications tab shows all the currently running applications. If you have an application that locked up, this is the first tab I would recommend going to. The software being used is listed in the window under the task column, and the status column will show either “Running” or “Not Responding.” Here you can highlight the unresponsive software and click on the End Task button, and after a few seconds the application will close; and depending on your settings, a dialogue box will appear and ask if you want to send a report to Microsoft. This procedure should take care of most lockups on the system, and it will bring Windows back to its normal functionality without having to shutdown and restart.

Also in this section you can run a new task or switch to another task to bring it to the front if you have multiple windows open.

The Processes Tab

The Processes tab is a little more powerful and more information-ridden. All applications and tasks running in the background are listed here, as well how much memory each task is using including how many CPU cycles it uses. If you are running low on system resources here you can find which tasks are causing the problem. The best way of determining if processes are being a system hog is to look at the amount of memory being used and look at the process and determine if it’s necessary. For example, processes virus scans that are running in the background while you are writing an article or doing some video editing obviously are not needed and you can shut them down temporarily and gain back some memory as well as some CPU power. You can shut down the non-critical tasks to give you back some memory or CPU power if need be. Windows starts a lot of tasks, and some of them are not necessary; shutting these extra tasks gives you back some memory and CPU cycles, thus more overall system performance. Don’t, however, try to end tasks that are SYSTEM tasks; sometimes they have random results and ending them could make more problems than it could solve. For example, shutting down the EXPLORER tasks will produce a non-working system because the taskbar and windows and icons will disappear. User tasks are okay to shut down, and if you do want to close a system task, make sure you understand what it does before you decide to close it. If you are not sure about a task and if it’s safe to close, do a Google search for the process and the detailed information will make it clear if you want or can shut it down.

The Performance Tab

Finally there is the Performance tab. This tab does just want it says—it monitors, in real time, the performance of the system. Specifically, the memory usage is monitored here. You will find information about total system memory and how much of it is in use and how much is left. CPU usage also is shown here, and if you keep this window open and use the PC, you will see the graph move in real time in relation to work being done on the computer. This window allows you to see in real time how a change that you make has an effect on your system. You can see immediately in the processes tab how closing non-critical tasks restores some CPU power as well as see how much system memory is left for other applications If you tweaked your system and you see that you are running low on memory, you can pinpoint it to the last application you opened and see if it’s a poorly written application or you have a memory leak somewhere. By going back to the processes tab and closing tasks one by one you can check the performance tab to see if makes a difference on the system.

The task manager can be a powerful tool to manage your overall system health or can be used to monitor you system for problems, even though there are more freeware/shareware programs out there that may do it better, but the task manager is free and it’s easy-to-use once you understand what you are looking at.

Click here to discuss this article in SysOpt's community forum.

If there is an optimization topic that you'd like to see addressed on SysOpt, let us know.

 

Source:

http://www.sysopt.com/articles/TaskManager/index.html



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Friday, June 10, 2005

Glossary of Digital media

A glossary of terms related to the Digital media industry.

Click on a term to read its desription.

Source: http://www.afterdawn.com/glossary/

Regards,

bharath

---------------------------------------------------------------------------------

Select a term to see the explanation

  • 1080i
  • 16:9
  • 2-pass
  • 3GP
  • 3ivX
  • 4:3
  • 720i
  • 720p
  • AAC
  • ABR
  • AC3
  • Advanced Simple Profile
  • AIFF
  • Anamorphic
  • Angles
  • ASF
  • Asian Silvers
  • Aspect ratio
  • ASPI
  • ASX
  • AUDIO_TS
  • Authoring
  • AVC
  • AVI
  • B Frames
  • BetaMax
  • BIN/CUE Images
  • Bitrate
  • BitTorrent
  • Blu-Ray
  • Bootlegs
  • Cam
  • Capture
  • CBR
  • CCE
  • CD+G
  • CD-DA
  • CD-Plus
  • CDA
  • CDV
  • cDVD
  • CGA
  • Chanserv
  • Chaoji VCD
  • Chapters
  • China Video Disc
  • CIF
  • Coaster
  • Codec
  • Combo Drive
  • Compression
  • Container
  • Cropping
  • CSS
  • CVD
  • D1
  • DAT
  • DCC Get
  • DCC Send
  • Decode
  • Deinterlace
  • Demultiplexing
  • Demux
  • Digital Rights Management
  • Digital8
  • DivX
  • DIVX (original)
  • DivX ;-)
  • DMCA
  • Dolby
  • Dolby Digital
  • DRM
  • DSDL
  • DSML
  • DSSL
  • DTS
  • DTV
  • DVB
  • DVB-C
  • DVB-H
  • DVB-S
  • DVB-T
  • DVCD
  • DVD
  • DVD+R
  • DVD+R DL
  • DVD+RW
  • DVD-10
  • DVD-14
  • DVD-18
  • DVD-5
  • DVD-9
  • DVD-Audio
  • DVD-MP3
  • DVD-R
  • DVD-R DL
  • DVD-R9
  • DVD-RAM
  • DVD-Rip
  • DVD-RW
  • DVD-SVCD
  • DVD-VCD
  • DVD-Video
  • DVD/TV Combo
  • DVI
  • DVI-A
  • DVI-D
  • DVI-I
  • EAC
  • ed2k
  • EDGE
  • Elementary Streams
  • Encode
  • EZ-D
  • FastTrack
  • FireWire
  • Firmware
  • FLAC
  • FourCC
  • fps
  • Frame
  • Framerate
  • Frameserve
  • Fserves
  • GPRS
  • H.264
  • Half D1
  • HD-DVD
  • HDTV
  • HE-AAC
  • Hi8
  • HQ-VCD
  • I Frame
  • ID3
  • IEEE.1394
  • IFO
  • IFPI
  • Interlace
  • Interleaving
  • INTERNAL
  • Inverse Telecine
  • IRC
  • ISO
  • ISO 9660
  • IVTC
  • KVCD
  • LAME
  • LaserDisc
  • Letterbox
  • Limited
  • Linear PCM
  • Lossless Compression
  • Lossy Compression
  • LPCM
  • M-JPEG
  • M1V
  • M2V
  • M3U
  • M4IF
  • Macrovision
  • MD5
  • MIDI
  • miniDV
  • miniDVD
  • Motion Estimation
  • Mount Rainier
  • MOV
  • MP2
  • MP3
  • MP3+G
  • MPA
  • MPAA
  • MPEG
  • MPEG-1
  • MPEG-2
  • MPEG-21
  • MPEG-4
  • MPEG-7
  • MPV
  • Multi-pass encoding
  • Multiplexing
  • Musepack (MP+)
  • Muxing
  • NFO
  • Nickserv
  • Noise
  • NTSC
  • NUKED
  • Ogg
  • Ogg Tarkin
  • Ogg Theora
  • Ogg Vorbis
  • OGM
  • Overburn
  • Overlay
  • P2P
  • PAL
  • Pan & Scan
  • PDVD
  • Pixels
  • Progressive
  • PROPER
  • QCIF
  • QuickTime
  • RAMDAC
  • RAR
  • RAW
  • RealVideo
  • Region code
  • REPACK
  • Resolution
  • RIAA
  • RIFF-WAV
  • RPC-1
  • RPC-2
  • SACD
  • SBR
  • Screener
  • SECAM
  • SFV
  • Simple Profile
  • SNR
  • SSDL
  • SSSL
  • Streaming
  • STV
  • SuperAudioCD
  • SuperVCD
  • SuperVHS
  • SuperVideoCD
  • SVCD
  • SVHS
  • Telecide
  • Telecine
  • Telesync
  • THX
  • torrent
  • Transcoding
  • TV-RIP
  • UDF
  • UMD
  • V2000
  • VBR
  • VCD
  • VHS
  • VHSRip
  • VideoCD
  • VIDEO_TS
  • VOB
  • Vorbis
  • VP3
  • VQF
  • WAV
  • Widescreen
  • Windows Media
  • WMA
  • WMV
  • Workprint
  • Wrapper
  • XCD
  • XDCC Bots
  • XSVCD
  • XVCD
  • XviD
  • ZIP

  •  


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    Wednesday, June 08, 2005

    The size of the Internet

    The size of the Internet

    Although the Internet is the newest medium for information flows, it is the fastest growing new medium of all time, and becoming the information medium of first resort for its users. Note that the Web consists of the surface web (fixed web pages) and what Bright Planet calls the deep web (the database driven websites that create web pages on demand).

    Table 8.1: The size of the Internet in terabytes.

    Medium

    2002 Terabytes

    Surface Web

    167

    Deep Web

    91,850

    Email (originals)

    440,606

    Instant messaging

    274

    TOTAL

    532,897

    Source: How much information 2003

     

    Worldwide stat on Internet usage:

    Source: Nielsen/NetRatings via CyberAtlas

     

    Compostition of surface web:


    Source: How much information 2003

     

     

    Spam count:

     


    Source: BrightMail
    http://www.brightmail.com/spamstats.html

    Source:

    http://www.sims.berkeley.edu/research/projects/how-much-info-2003/internet.htm

     

    Note:

    This compilation is based on the survey data collected in 2003.These are not current data.If anyone has access to current data on the above topics,please send to me or post as a comment in my blog.

     



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    Google Pagerank Algorithm

    The Google Pagerank Algorithm
    and How It Works

    Ian Rogers
    IPR Computing Ltd.
    ian@iprcom.com

    Introduction

    Page Rank is a topic much discussed by Search Engine Optimisation (SEO) experts. At the heart of PageRank is a mathematical formula that seems scary to look at but is actually fairly simple to understand.

    Despite this many people seem to get it wrong! In particular “Chris Ridings of www.searchenginesystems.net” has written a paper entitled “PageRank Explained: Everything you’ve always wanted to know about PageRank”, pointed to by many people, that contains a fundamental mistake early on in the explanation! Unfortunately this means some of the recommendations in the paper are not quite accurate.

    By showing code to correctly calculate real PageRank I hope to achieve several things in this response:

    1. Clearly explain how PageRank is calculated.
    2. Go through every example in Chris’ paper, and add some more of my own, showing the correct PageRank for each diagram. By showing the code used to calculate each diagram I’ve opened myself up to peer review - mostly in an effort to make sure the examples are correct, but also because the code can help explain the PageRank calculations.
    3. Describe some principles and observations on website design based on these correctly calculated examples.

    Any good web designer should take the time to fully understand how PageRank really works - if you don’t then your site’s layout could be seriously hurting your Google listings!

    [Note: I have nothing in particular against Chris. If I find any other papers on the subject I’ll try to comment evenly]

    How is PageRank Used?

    PageRank is one of the methods Google uses to determine a page’s relevance or importance. It is only one part of the story when it comes to the Google listing, but the other aspects are discussed elsewhere (and are ever changing) and PageRank is interesting enough to deserve a paper of its own.

    PageRank is also displayed on the toolbar of your browser if you’ve installed the Google toolbar (http://toolbar.google.com/). But the Toolbar PageRank only goes from 0 – 10 and seems to be something like a logarithmic scale:

    Toolbar PageRank
    (log base 10)

    Real PageRank

    0

    0 - 10

    1

    100 - 1,000

    2

    1,000 - 10,000

    3

    10,000 - 100,000

    4

    and so on...

    We can’t know the exact details of the scale because, as we’ll see later, the maximum PR of all pages on the web changes every month when Google does its re-indexing! If we presume the scale is logarithmic (although there is only anecdotal evidence for this at the time of writing) then Google could simply give the highest actual PR page a toolbar PR of 10 and scale the rest appropriately.

    Also the toolbar sometimes guesses! The toolbar often shows me a Toolbar PR for pages I’ve only just uploaded and cannot possibly be in the index yet!

    What seems to be happening is that the toolbar looks at the URL of the page the browser is displaying and strips off everything down the last “/” (i.e. it goes to the “parent” page in URL terms). If Google has a Toolbar PR for that parent then it subtracts 1 and shows that as the Toolbar PR for this page. If there’s no PR for the parent it goes to the parent’s parent’s page, but subtracting 2, and so on all the way up to the root of your site.  If it can’t find a Toolbar PR to display in this way, that is if it doesn’t find a page with a real calculated PR, then the bar is greyed out.

    Note that if the Toolbar is guessing in this way, the Actual PR of the page is 0 - though its PR will be calculated shortly after the Google spider first sees it.

    PageRank says nothing about the content or size of a page, the language it’s written in, or the text used in the anchor of a link!

    Definitions

    I’ve started to use some technical terms and shorthand in this paper. Now’s as good a time as any to define all the terms I’ll use:

    PR:

    Shorthand for PageRank: the actual, real, page rank for each page as calculated by Google. As we’ll see later this can range from 0.15 to billions.

    Toolbar PR:

    The PageRank displayed in the Google toolbar in your browser. This ranges from 0 to 10.

    Backlink:

    If page A links out to page B, then page B is said to have a “backlink” from page A.

    That’s enough of that, let’s get back to the meat…

    So what is PageRank?

    In short PageRank is a “vote”, by all the other pages on the Web, about how important a page is. A link to a page counts as a vote of support. If there’s no link there’s no support (but it’s an abstention from voting rather than a vote against the page).

    Quoting from the original Google paper, PageRank is defined like this:

      We assume page A has pages T1...Tn which point to it (i.e., are citations). The parameter d is a damping factor which can be set between 0 and 1. We usually set d to 0.85. There are more details about d in the next section. Also C(A) is defined as the number of links going out of page A. The PageRank of a page A is given as follows:

      PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))

      Note that the PageRanks form a probability distribution over web pages, so the sum of all web pages' PageRanks will be one.

      PageRank or PR(A) can be calculated using a simple iterative algorithm, and corresponds to the principal eigenvector of the normalized link matrix of the web.

    but that’s not too helpful so let’s break it down into sections.

    1. PR(Tn) - Each page has a notion of its own self-importance. That’s “PR(T1)” for the first page in the web all the way up to “PR(Tn)” for the last page
    2. C(Tn) - Each page spreads its vote out evenly amongst all of it’s outgoing links. The count, or number, of outgoing links for page 1 is “C(T1)”, “C(Tn)” for page n, and so on for all pages.
    3. PR(Tn)/C(Tn) - so if our page (page A) has a backlink from page “n” the share of the vote page A will get is “PR(Tn)/C(Tn)”
    4. d(... - All these fractions of votes are added together but, to stop the other pages having too much influence, this total vote is “damped down” by multiplying it by 0.85 (the factor “d”)
    5. (1 - d) - The (1 – d) bit at the beginning is a bit of probability math magic so the “sum of all web pages' PageRanks will be one”: it adds in the bit lost by the d(.... It also means that if a page has no links to it (no backlinks) even then it will still get a small PR of 0.15 (i.e. 1 – 0.85). (Aside: the Google paper says “the sum of all pages” but they mean the “the normalised sum” – otherwise known as “the average” to you and me.

    How is PageRank Calculated?

    This is where it gets tricky. The PR of each page depends on the PR of the pages pointing to it. But we won’t know what PR those pages have until the pages pointing to them have their PR calculated and so on… And when you consider that page links can form circles it seems impossible to do this calculation!

    But actually it’s not that bad. Remember this bit of the Google paper:

      PageRank or PR(A) can be calculated using a simple iterative algorithm, and corresponds to the principal eigenvector of the normalized link matrix of the web.

    What that means to us is that we can just go ahead and calculate a page’s PR without knowing the final value of the PR of the other pages. That seems strange but, basically, each time we run the calculation we’re getting a closer estimate of the final value. So all we need to do is remember the each value we calculate and repeat the calculations lots of times until the numbers stop changing much.

    Lets take the simplest example network: two pages, each pointing to the other:

    Each page has one outgoing link (the outgoing count is 1, i.e. C(A) = 1 and C(B) = 1).

     

    Guess 1

    We don’t know what their PR should be to begin with, so let’s take a guess at 1.0 and do some calculations:

    d

    = 0.85

    PR(A)

    = (1 – d) + d(PR(B)/1)

    PR(B)

    = (1 – d) + d(PR(A)/1)

    i.e.

    PR(A)

    = 0.15 + 0.85 * 1
    = 1

    PR(B)

    = 0.15 + 0.85 * 1
    = 1

    Hmm, the numbers aren’t changing at all! So it looks like we started out with a lucky guess!!!

    Guess 2

    No, that’s too easy, maybe I got it wrong (and it wouldn’t be the first time). Ok, let’s start the guess at 0 instead and re-calculate:

    PR(A)

    = 0.15 + 0.85 * 0
    = 0.15

     

    PR(B)

    = 0.15 + 0.85 * 0.15
    = 0.2775

    NB. we’ve already calculated a “next best guess” at PR(A) so we use it here

    And again:

    PR(A)

    = 0.15 + 0.85 * 0.2775
    = 0.385875

    PR(B)

    = 0.15 + 0.85 * 0.385875
    = 0.47799375

    And again

    PR(A)

    = 0.15 + 0.85 * 0.47799375
    = 0.5562946875

    PR(B)

    = 0.15 + 0.85 * 0.5562946875
    = 0.622850484375

    and so on. The numbers just keep going up. But will the numbers stop increasing when they get to 1.0? What if a calculation over-shoots and goes above 1.0?

     

    Guess 3

    Well let’s see. Let’s start the guess at 40 each and do a few cycles:

      PR(A) = 40
      PR(B) = 40

    First calculation

    PR(A)

    = 0.15 + 0.85 * 40
    = 34.25

    PR(B)

    = 0.15 + 0.85 * 0.385875
    = 29.1775

    And again

    PR(A)

    = 0.15 + 0.85 * 29.1775
    = 24.950875

    PR(B)

    = 0.15 + 0.85 * 24.950875
    = 21.35824375

    Yup, those numbers are heading down alright! It sure looks the numbers will get to 1.0 and stop

    Here’s the code used to calculate this example starting the guess at 0: Show the code | Run the program

    • Principle: it doesn’t matter where you start your guess, once the PageRank calculations have settled down, the “normalized probability distribution” (the average PageRank for all pages) will be 1.0

     

    Getting the answer quicker

    How many times do we need to repeat the calculation for big networks? That’s a difficult question; for a network as large as the World Wide Web it can be many millions of iterations! The “damping factor” is quite subtle. If it’s too high then it takes ages for the numbers to settle, if it’s too low then you get repeated over-shoot, both above and below the average - the numbers just swing about the average like a pendulum and never settle down.

    Also choosing the order of calculations can help. The answer will always come out the same no matter which order you choose, but some orders will get you there quicker than others.

    I’m sure there’s been several Master’s Thesis on how to make this calculation as efficient as possible, but, in the examples below, I’ve used very simple code for clarity and roughly 20 to 40 iterations were needed!

     

    Example 1

    I’m not going to repeat the calculations here, but you can see them by running the program (yes, if you click the link the program really is re-run to do the calculations for you)

    So the correct PR for the example is:

    You can see it took about 20 iterations before the network began to settle on these values!

    Look at Page D though - it has a PR of 0.15 even though no-one is voting for it (i.e. it has no incoming links)! Is this right?

    The first part, or "term" to be techinal, of the PR equation is doing this:

      PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))

    So, for Page D, no backlinks means the equation looks like this:

    PR(A)

    = (1-d) + d * (0)
    = 0.15

    no matter what else is going on or how many times you do it.

      Observation: every page has at least a PR of 0.15 to share out. But this may only be in theory - there are rumours that Google undergoes a post-spidering phase whereby any pages that have no incoming links at all are completely deleted from the index...

       

    Example 2

    A simple hierarchy with some outgoing links

    As you’d expect, the home page has the most PR – after all, it has the most incoming links! But what’s happened to the average? It’s only 0.378!!! That doesn’t tie up with what I said earlier so something is wrong somewhere!

    Well no, everything is fine. But take a look at the “external site” pages – what’s happening to their PageRank? They’re not passing it on, they’re not voting for anyone, they’re wasting their PR like so much pregnant chad!!! (NB, a more accurate description of this issue can be found in this thread)

     

    Example 3

    Let’s link those external sites back into our home page just so we can see what happens to the average…

    That’s better - it does work after all! And look at the PR of our home page! All those incoming links sure make a difference – we’ll talk more about that later.

     

    Example 4

    What happens to PR if we follow a suggestion about writing page reviews?

     

     

    Example 5

    A simple hierarchy

    Our home page has 2 and a half times as much PR as the child pages! Excellent!

    • Observation: a hierarchy concentrates votes and PR into one page

     

    Example 6

    Looping

    This is what we’d expect. All the pages have the same number of incoming links, all pages are of equal importance to each other, all pages get the same PR of 1.0 (i.e. the “average” probability).

     

    Example 7

    Extensive Interlinking – or Fully Meshed

    Yes, the results are the same as the Looping example above and for the same reasons.

     

    Example 8

    Hierarchical – but with a link in and one out.

    We’ll assume there’s an external site that has lots of pages and links with the result that one of the pages has the average PR of 1.0. We’ll also assume the webmaster really likes us – there’s just one link from that page and it’s pointing at our home page.

    In example 5 the home page only had a PR of 1.92 but now it is 3.31! Excellent! Not only has site A contributed 0.85 PR to us, but the raised PR in the “About”, “Product” and “More” pages has had a lovely “feedback” effect, pushing up the home page’s PR even further!

    • Priciple: a well structured site will amplify the effect of any contributed PR

     

    Example 9

    Looping – but with a link in and a link out

    Well, the PR of our home page has gone up a little, but what’s happened to the “More” page?

    The vote of the “Product” page has been split evenly between it and the external site. We now value the external Site B equally with our “More” page. The “More” page is getting only half the vote it had before – this is good for Site B but very bad for us!

     

    Example 10

    Fully meshed – but with one vote in and one vote out

    That’s much better. The “More” page is still getting less share of the vote than in example 7 of course, but now the “Product” page has kept three quarters of its vote within our site - unlike example 10 where it was giving away fully half of it’s vote to the external site!

    Keeping just this small extra fraction of the vote within our site has had a very nice effect on the Home Page too – PR of 2.28 compared with just 1.66 in example 10.

    • Observation: increasing the internal links in your site can minimise the damage to your PR when you give away votes by linking to external sites.
    • Principle:
      • If a particular page is highly important – use a hierarchical structure with the important page at the “top”.
      • Where a group of pages may contain outward links – increase the number of internal links to retain as much PR as possible.
      • Where a group of pages do not contain outward links – the number of internal links in the site has no effect on the site’s average PR. You might as well use a link structure that gives the user the best navigational experience.

     

    Site Maps

    Site maps are useful in at least two ways:

    • If a user types in a bad URL most websites return a really unhelpful “404 – page not found” error page. This can be discouraging. Why not configure your server to return a page that shows an error has been made, but also gives the site map? This can help the user enormously
    • Linking to a site map on each page increases the number of internal links in the site, spreading the PR out and protecting you against your vote “donations”

     

    Example 11

    Lets try to fix our site to artificially concentrate the PR into the home page.

    That looks good, most of the links seem to be pointing up to page A so we should get a nice PR.

     

    Try to guess what the PR of A will be before you scroll down or run the code.

     

     

    Oh dear, that didn’t work at all well – it’s much worse than just an ordinary hierarchy! What’s going on is that pages C and D have such weak incoming links that they’re no help to page A at all!

    • Principle: trying to abuse the PR calculation is harder than you think.

     

    Example 12

    A common web layout for long documentation is to split the document into many pages with a “Previous” and “Next” link on each plus a link back to the home page. The home page then only needs to point to the first page of the document.

    In this simple example, where there’s only one document, the first page of the document has a higher PR than the Home Page! This is because page B is getting all the vote from page A, but page A is only getting fractions of pages B, C and D.

    • Principle: in order to give users of your site a good experience, you may have to take a hit against your PR. There’s nothing you can do about this - and neither should you try to or worry about it! If your site is a pleasure to use lots of other webmasters will link to it and you’ll get back much more PR than you lost.

    Can you also see the trend between this and the previous example? As you add more internal links to a site it gets closer to the Fully Meshed example where every page gets the average PR for the mesh.

    • Observation: as you add more internal links in your site, the PR will be spread out more evenly between the pages.

     

    Example 13

    Getting high PR the wrong way and the right way.

    Just as an experiment, let’s see if we can get 1,000 pages pointing to our home page, but only have one link leaving it…

    Yup, those spam pages are pretty worthless but they sure add up!

    • Observation: it doesn’t matter how many pages you have in your site, your average PR will always be 1.0 at best. But a hierarchical layout can strongly concentrate votes, and therefore the PR, into the home page!

    This is a technique used by some disreputable sites (mostly adult content sites). But I can’t advise this - if Google’s robots decide you’re doing this there’s a good chance you’ll be banned from Google! Disaster!

    On the other hand there are at least two right ways to do this:

    1. Be a Mega-site

    Mega-sites, like http://news.bbc.co.uk have tens or hundreds of editors writing new content – i.e. new pages - all day long! Each one of those pages has rich, worthwile content of its own and a link back to its parent or the home page! That’s why the Home page Toolbar PR of these sites is 9/10 and the rest of us just get pushed lower and lower by comparison…

    • Principle: Content Is King! There really is no substitute for lots of good content…

     

    2. Give away something useful

    www.phpbb.com has a Toolbar PR of 8/10 (at the time of writing) and it has no big money or marketing behind it! How can this be?

    What the group has done is write a very useful bulletin board system that is becoming very popular on many websites. And at the bottom of every page, in every installation, is this HTML code:

    Powered by <a href="http://www.phpbb.com/" target="_blank">phpBB</a>

    The administrator of each installation can remove that link, but most don’t because they want to return the favour…

    Can you imagine all those millions of pages giving a fraction of a vote to www.phpbb.com? Wow!

    • Principle: Make it worth other people’s while to use your content or tools. If your give-away is good enough other site admins will gladly give you a link back.
    • Principle: it’s probably better to get lots (perhaps thousands) of links from sites with small PR than to spend any time or money desperately trying to get just the one link from a high PR page.

     

    A Discussion on Averages

    From the Brin and Page paper, the average Actual PR of all pages in the index is 1.0!

    So if you add pages to a site you’re building the total PR will go up by 1.0 for each page (but only if you link the pages together so the equation can work), but the average will remain the same.

    If you want to concentrate the PR into one, or a few, pages then hierarchical linking will do that. If you want to average out the PR amongst the pages then "fully meshing" the site (lots of evenly distributed links) will do that - examples 5, 6, and 7 in my above. (NB. this is where Ridings’ goes wrong, in his MiniRank model feedback loops will increase PR - indefinitely!)

    Getting inbound links to your site is the only way to increase your site's average PR. How that PR is distributed amongst the pages on your site depends on the details of your internal linking and which of your pages are linked to.

    If you give outbound links to other sites then your site's average PR will decrease (you're not keeping your vote "in house" as it were). Again the details of the decrease will depend on the details of the linking.

    Given that the average of every page is 1.0 we can see that for every site that has an actual ranking in the millions (and there are some!) there must be lots and lots of sites who's Actual PR is below 1.0 (particularly because the absolute lowest Actual PR available is (1 - d)).

    It may be that the Toolbar PR 1,2 correspond to Actual PR's lower than 1.0! E.g. the logbase for the Toolbar may be 10 but the Actual PR sequence could start quite low: 0.01, 0.1, 1, 10, 100, 1,000 etc...

    Finally

    PageRank is, in fact, very simple (apart from one scary looking formula). But when a simple calculation is applied hundreds (or billions) of times over the results can seem complicated.

    PageRank is also only part of the story about what results get displayed high up in a Google listing. For example there’s some evidence to suggest that Google is paying a lot of attention these days to the text in a link’s anchor when deciding the relevance of a target page – perhaps more so than the page’s PR…

    PageRank is still part of the listings story though, so it’s worth your while as a good designer to make sure you understand it correctly.

     

    Links

    About the Author

    Ian Rogers first used the Internet in 1986 sending email on a University VAX machine! He first installed a webserver in 1990, taught himself HTML and perl CGI scripting. Since then he has been a Senior Research Fellow in User Interface Design and a consultant in Network Security and Database Backed Websites. He has had an informal interest in topology and the mathematics and behaviour of networks for years and has also been known to do a little Jive dancing.

    This paper was sponsored by IPR Computing Ltd – specialists in Secure Networks and Database Backed Websites



      My Email :  bharath_m_7@yahoo.co.in 
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    Friday, June 03, 2005

    Difference between DVD+RW and DVD-RW

    As per my analysis,
    Most of the DVD writers are compatible with both
    DVD+RW/DVD+R format as well as the DVD-RW/DVD-R
    format.
    It will be specified collectively as DVD±RW.

    The difference between them is that these formats are
    supported and created by different groups of
    companies.

    DVD+RW/DVD+R is supported by "DVD+RW Alliance".
    URL: http://www.dvdrw.com/

    DVD-RW/DVD-R is supported by "DVD Forum".
    URL: http://www.dvdforum.com/forum.shtml

    Thats all.

    Comments are welcome.

    Regards,
    bharath

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    DVD File/Folder Structure

    DVD File/Folder Structure

    Explanation:

    . BUP = Backup files of the IFO files.

    . IFO = The IFO files includes information such as chapters, subtitle tracks and audio tracks.

    . VOB = The VOB files contains the actual video,audio,subtitles and menus.

    Folder Files Explanation
    AUDIO_TS (undefined) DVD Audio
    VIDEO_TS VIDEO_TS.BUP  
      VIDEO_TS.IFO
    The first video play item, IFO, usally a copyright notice or a menu
      VIDEO_TS.VOB The first video play item, VOB
      VTS_01_0.BUP  
      VTS_01_0.IFO Title 01, IFO, usually the main movie
      VTS_01_0.VOB Title 01, VOB 0, the menu for this title
      VTS_01_1.VOB Title 01, VOB 1, the video for this title
      VTS_01_2.VOB Title 01, VOB 2, if larger than 1 GB it will be splitted into several vobs
      VTS_01_3.VOB Title 01, VOB 3
      VTS_01_4.VOB Title 01, VOB 4, up to 10(0-9) VOB files if necassary
      VTS_02_0.BUP  
      VTS_02_0.IFO Title 02, IFO, usually movie extras
      VTS_02_0.VOB Title 02, VOB 0, the menu for this title
      VTS_02_1.VOB Title 02, VOB 1, the video for this title
      VTS_xx_x.BUP  
      VTS_xx_x.IFO And so on
      VTS_xx_x.VOB  
      VTS_xx_x.VOB  
      VTS_99_9.VOB Up to 99(1-99) titles with max 10(0-9) VOB files each



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