[TriLUG] Help

[Aaron S. Joyner]

Jason Tower wrote:

>it *sounds* like a DNS issue.  don't know if you're using a hostname to 
>reach the apache server, or an IP address, or (god forbid) a netbios 
>name, but that's where i'd start looking.
>
>jason
>
>On Wednesday 07 July 2004 11:18, Caren Smith wrote:
>  
>
>>I have an apache web server running on red hat 9.  There are 2
>>internal networks trying to reach this server.  One gets an answer
>>within 1 second and the other takes 20 seconds.  The server is
>>directly connected to a switch.  I sniffed the line between the
>>server and the switch and saw the 20 second delay which leads me to
>>believe it is something on the box itself that's causing the delay. 
>>Can someone point me in the right direction?
>>
>>    
>>
As Jason suggests, it sounds like DNS resolution.  But your webserver 
shouldn't be trying to do DNS reverse lookups on connecting clients 
before returning the page to them.  You mention that these are two 
different "networks" connecting to the Apache server.  I wonder how 
accurate that statement is, because if it's really two networks (as 
opposed to just two machines), have you considered that those two 
machines may have different DNS server set ups?  Do they get different 
information from different DHCP servers, or are they statically 
configured differently?  Does the "slow" network have to time out 
through a DNS query before it hits the server at all?

You said you sniffed the traffic going into the webserver -- where was 
the pause, in the session?

* Was it after the initial connection, but before *any* response from 
the server?  This would lead me to believe it might be an access-rights 
issue w/ Apache.  Are you limiting access via hostname with mod_access?

* Was it after the client's request but before handing back the data 
that was requested?  Do you have Apache setup to log DNS entries to the 
logs for each connect (not the default, for sure - look at 
HostnameLookups).  There are other considerations here that can cause 
weirdness, esp. if you're doing dynamic pages or some such -- but I 
suspect that you'd have mentioned that in your message.

Either way, these suggestions resolve around DNS issues.  Check your 
/etc/resolv.conf and make sure your "nameserver 1.2.3.4" lines are valid 
nameservers and can resolve the addresses your connecting from.

Aaron S. Joyner