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I cannot access a certain website. There are two possible reasons:

  1. The block is on the ISP side.
  2. The block is at the website.

Is there a technical way to figure out which of these are causing the problem?

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closed as not a real question by HopelessN00b, Dave M, Greg Askew, TheCleaner, Bryan Feb 6 '13 at 16:36

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

    
We would need more information. If possible what is the website/domain name? The IP address? How you are trying to access it?is there any firewall's in place? What browser and ISP do you use? –  Zippyduda Feb 6 '13 at 11:24
    
Actually, there are a lot more than just those two possibilities, but without more information... much, much, much more information, this isn't answerable. Or at all useful or constructive. –  HopelessN00b Feb 6 '13 at 13:26
    
This is a general question, not related to a specific website. –  bosh Feb 6 '13 at 14:42
    
I understand that there are plenty of other options of things that can go wrong, but let's assume for the moment that these are the only two options. –  bosh Feb 6 '13 at 14:44
    
@bosh we can't assume those are the possibilities - you need to give us proper troubleshooting information. Otherwise the answer to your question is "Call your ISP. If they say it's not them, call the website owner/operator" –  voretaq7 Feb 6 '13 at 16:35

1 Answer 1

It's hard to say without more information, but here are some general things to try:

0) lookup the website hostname (e.g. on windows execute "nslookup www.example.com," or, on os-x or *nix execute "host www.example.com". If you don't get an IP address response, that means your webserver system isn't registered in DNS.

1) Next ping the webserver. I.e. ping the hostname of the server running the website. If you get a response, that at least tells you there is an open network path (at least for ping) between your client and the web server. If you don't get a response, it could be that only ping is blocked, but most likely the server is just unreachable for some reason. It could be down.

2) Next, try to establish an HTTP connection to the website. You can use a browser and look at what happens (e.g. do you get an error, like 500, or does it just sit there and time out?). If it's a website that should be globally-reachable, at this point you might also consider using a service like DownForEveryoneOrJustMe.com This will help identify if the problem is only on your end (i.e. the client) or if the site is down for others (at least for the "DownForEveryoneOrJustMe.com" server.)

3) If you're unable to establish a connection, at this point it might be wise to kick off tcpdump or wireshark on your client (and/or on the web server if you have console and admin access) while you attempt to open a connection. This will allow you to see if TCP packets are getting to the server and how the server is responding. You'll get more clues then.

4) If the server is not responding to HTTP (TCP port 80) packets, it could be a firewall silently dropping the packets. But, it's also possible the machine isn't running an HTTPD daemon (e.g. apache). So, if you have admin rights on the server, you could look at the process table (using 'ps -aux | grep "http"' if it's *nix). If a daemon is running, the next place to look is the logs for apache or whatever web server software is being run. Etc.

If you give us more information, especially what you tried and what works or doesn't we can try to help you more. Good luck.

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