Gateway Timeout

[lobos]

Gateway Timeout
The following error occurred:

[code=DNS_TIMEOUT] A DNS lookup error occurred because the request timed out during the lookup.
Please contact the administrator.
------------------

CAn someone tell me what this means? I am getting it a lot on my server account for some urls - eg I can go to www.themes.co.nz but at the moment if I access http://themes.co.nz/pnphpbb2.htm I get the above error...

Is this a problem for my IP or is it a server problem?

Thanks,

-Lobos

[jason]

Where are you getting this error? Is it from a piece of software on your local machine, a script on your server, etc.?

It looks like a problem with DNS resolution, but without knowing where the error is coming from it is impossible to say much more.

--Jason

[lobos]

Hi there,

it is from the postnuke pnphpbb2 forum module. I don't feel that the script is the problem becuase it works perfectly - this error comes up every so often during the day. It also happens on some other pages every so often. Bascially I just want ot know if it is the server or my internet provider (i think it's the IP, but I thought I would ask here).

-Lobos

[Spathiphyllum]

Do you use Firefox? If so, go to their addons page and search for Live HTTP Headers. Install the tool. This will allow you to view the response headers for every GET request submitted by your client (i.e. the browser).

When you load a page, review the list of responses from LiveHTTPHeaders and note the code provided for each resource received. From that, you should at least be able to tell from where the trouble for DNS resolution is originating. If your site partially renders, but content being pulled from another domain is slowing things down, you might be able to tell which site isn't having its DNS resolve in a timely manner. If you don't even get a page but receive instead some caching proxy default error page, you can probably conclude that it is a more local DNS issue (read local ISP) instead and that they may have their DNS server operating suboptimally.

Or you could try a computer on another network (different ISP) and see if the issue persists. If it does, it's probably site related. If it doesn't, then it's probably ISP related.

Try these for starters.

[Spathiphyllum]

As an example from the URL you provided:

http://themes.co.nz/pnphpbb2.htm

GET /pnphpbb2.htm HTTP/1.1
Host: themes.co.nz
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.1.2) Gecko/20070219 Firefox/2.0.0.2
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive

HTTP/1.x 200 OK
Date: Wed, 28 Feb 2007 21:20:33 GMT
Server: Apache/1.3.37 (Unix) mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 FrontPage/5.0.2.2635.SR1.2 mod_ssl/2.8.28 OpenSSL/0.9.7a PHP-CGI/0.1b
Cache-Control: private, pre-check=0, post-check=0, max-age=0
Expires: 0
Pragma: no-cache
X-Powered-By: PHP/4.4.4
Set-Cookie: POSTNUKESID=[snippage]; path=/
Set-Cookie: pnphpbb2mysql_data=[snippage]; path=/
Set-Cookie: pnphpbb2mysql_sid=[snippage]; path=/
Content-Type: text/html
X-Cache: MISS from local.localdomain
Connection: close
----------------------------------------------------------
http://themes.co.nz/themes/wte_nvida/images//favicon.ico

GET /themes/wte_nvida/images//favicon.ico HTTP/1.1
Host: themes.co.nz
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.1.2) Gecko/20070219 Firefox/2.0.0.2
Accept: image/png,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive

HTTP/1.x 404 Not Found
Date: Wed, 28 Feb 2007 21:20:45 GMT
Server: Apache/1.3.37 (Unix) mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 FrontPage/5.0.2.2635.SR1.2 mod_ssl/2.8.28 OpenSSL/0.9.7a PHP-CGI/0.1b
Content-Type: text/html; charset=iso-8859-1
X-Cache: MISS from local.localdomain
Connection: close
----------------------------------------------------------

Here are the first two GETS with their respective server replies to those GETs. Note that the first one is "OK" (Code 200) while the favicon.ico URL was not OK but rather "Not Found" (Code 404). From this we know that the HTML code was received by the client but that the subsequent request for the favicon.ico file was unfulfilled because the server could not find that resource on the server. Yes, favicon.ico exists on it, but the HTML code (or some Apache directive that redefines internal paths) that describes that resource path is incorrect and cannot be offered. The extra leading slash is an error which means that the file will not be found at the defined path.

This is how one uses LiveHTTPHeaders to trace issues. Now, this doesn't help you with your DNS issue, but it might help explain why there is a delay in page rendering since the server keeps looking for "/favicon.ico" instead of the correct "favicon.ico" resource on the server and cannot find it while wasting time in the process.

Hope this helps with tracking future issues. I did not observe any gateway timeout issues during my visit. Simply, this means that a server name on the route between your node and the target server could not be resolved for whatever reason. When the server could not be resolved (name to DNS), then the route for communication essentially died since the next node in the chain could not be reached. A server between you and the last successfully resolved host returned a default message to you to indicate that DNS resolution failed, and your browser rendered the notice.

[lobos]

Thank you very much for your detailed response - I really appreciate the time and effort you have donated me. I will now act on the information you have provided me.

-Lobos