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This morning, I tried to connect to stackoverflow.com, but failed. Then I used the command ping stackoverflow.com. It worked, got all the four replies and showed the IP address 198.252.206.16. So I type the address into my Chrome browser, but still failed. It says

'Couldn't find 198.252.206.16 The Q&A site 198.252.206.16 doesn't seem to exist…yet.

You can vote for it to be created through our democratic, community-driven process at area51.stackexchange.com, or see a complete directory of all our Q&A sites at stackexchange.com.

If you are the administrator of a Stack Exchange 1.0 site, please contact the community team with any questions you may have.'

As you see, I can connect to stackoverflow.com now. But I still cannot link to 198.252.206.16 with Chrome.

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    When you enter the IP address your browser won't send a proper host in the http request. – CodesInChaos May 14 '13 at 5:46
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StackExchange is likely using name-based virtual hosting. This means they're hosting multiple domains from the same IP address.

If you ping various SE sites, you will see many resolve to the same IP address.

For example, stackoverflow.com, stackexchange.com, superuser.com all resolve to 198.252.206.16.

The server decides which site to respond with based on the host field of the HTTP request (which is generally equal to the domain name you enter into your browser). Since it seems StackExchange hasn't associated a site to their raw IP address (i.e. a host value of 198.252.206.16), they present you with their default "site does not exist" page.

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  • thank you very much for your answer in detail – ray May 14 '13 at 6:10

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