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When I used the ping command to test my site, it shows OK.

ping result

When I access the site with ip or domain(, it shows Unable to connect. I put the site on a vps yesterday. The site sometimes can access, sometimes can't. what's the reason it maybe cause this?

When i use ftp to access the site, it works.

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migrated from Nov 16 '11 at 21:09

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8 … seriously? – knittl Nov 16 '11 at 14:03
Well, there's nothing wrong with the domain if he's selling sexy lingerie... – Polynomial Nov 16 '11 at 14:05
Can't be selling too much if the web server is down. ;) – John Gardeniers Nov 16 '11 at 23:48
You say that you can't connect to it by pointing a web browser to the IP, but yet two other domains hosted on the same VPS work fine? Could there be something like connection rate limiting or some such in place somewhere? Do the domains point at the exact same IP address? No round robin or the likes to mess things up? – Michael Kjörling Nov 17 '11 at 10:38

Pinging is not the same as visiting in a browser. For pinging the server only needs to accept ICMP requests, when visiting the site you do an HTTP request to the webserver at that ip. Much more happens.

So there are many things that could be wrong, including for example:

  • No webserver is installed or it is not accepting request for some reason
  • The server has a firewall which is preventing connections on port 80

Edit: If you are having intermittent problems, the above will probably not be the case. Then I really suggest you contact your VPS hoster about the problems you are having.

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ping uses ICMP, not TCP. – Farhan Nov 16 '11 at 14:08
thank you, but sometimes i can access the site, sometimes don't. there are three sites on my vps. the rest two works ok – dreamchaser Nov 16 '11 at 14:10
@Farhan True, although I think my idea was clear. I have modified my answer to comply though. – pyrocumulus Nov 16 '11 at 14:11
Servers don't 'accept ICMP connections', they process ICMP requests. ICMP is a connectionless protocol. – EJP Nov 17 '11 at 4:40
And modified again.. Although I really think everyone knows what I meant. – pyrocumulus Nov 17 '11 at 10:34

Ironically I have just dealt with this problem twice in one day on Linux and Windows. On Windows problem ended up being Anti-virus(Avast) Internet Scanner blocking port 80 traffic. One Linux box after clearing DNS cache in browser, and restarting network interface with no luck. I restart the networking service /etc/init.d/networking restart and it worked.

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If you can hit the site via ping and get access via FTP, the HTTP daemon is probably down. You should contact your provider and ask them about it.

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thank you, but sometimes i can access the site, sometimes don't. there are three sites on my vps. the rest two works ok – dreamchaser Nov 16 '11 at 14:08
Odd. Perhaps it's a firewall or NIC issue. – Polynomial Nov 16 '11 at 14:09

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