Re: DNS lookup failure for: hostname

["Robert Webb" <rwebb@xxxxxxxxxxxx>]

So are you running through the F5, load balancing to the two Apache proxies, 
then load balancing with the apache proxies to your 10 back end JBOSS 
servers?


On Wed, 22 Apr 2015 16:21:29 -0400
 Yasser <yarafatin@xxxxxxxxx> wrote:
> I am in the midst of performance testing a web application and I get 
> these
> errors in Apache logs
>
> [Sat Apr 18 03:01:01 2015] [error] [client xx.xx.xxx.253] proxy: DNS 
> lookup
> failure for: jboss-host-name returned by /some/url, referer:
> http://f5hostname/context/URI
>
> It occurs only at high load levels. I have seen posts where this 
> error
> occurs due to incorrect proxy configuration, but my case doesn't 
> fall under
> that I guess. At the very end of the test I get another error - "All
> workers are in error state". I think the first DNS error causes all 
> workers
> to shutdown.
>
> Can someone point where I could start looking? Please let me know if 
> you
> need more details than whats mentioned below.
>
> *More details:*
>
> Apache version: 2.2
>
> mod_cluster: 1.2.4.Final
>
> I have an F5 in front of two Apache servers. There are ten JBoss 
> servers in
> the balancer.
>
> Apache configuration snippet: (I am not using proxypass directive, 
> just
> modcluster)
>
> <IfModule mod_proxy.c>
>    ProxyRequests Off
>    ProxyVia On</IfModule>
> <IfModule mpm_worker_module>
>    ServerLimit, StartServers and worker related attributes 
> configured
> here</IfModule>
> ProxyPreserveHost OnMemManagerFile /var/cache/httpd
> <VirtualHost *:1280>
>    ManagerBalancerName some2 (this is the same usedin jboss using 
> proxylist)
>    ........
>
> Logs:
>
> [Tue Apr 21 22:06:25 2015] [debug] mod_proxy_http.c(1973): proxy: 
> HTTP:
> serving URL http://jbosshost:8080/uri
>
> [Tue Apr 21 22:06:25 2015] [debug] proxy_util.c(2011): proxy: HTTP: 
> has
> acquired connection for (jbosshost)
>
> [Tue Apr 21 22:06:25 2015] [debug] proxy_util.c(2067): proxy: 
> connecting
> http://jbosshost:8080/uri
>
> [Tue Apr 21 22:06:25 2015] [error] [client 10.xxx.xxx.xxx] proxy: 
> DNS
> lookup failure for: jbosshost returned by /URI
>
> [Tue Apr 21 22:06:25 2015] [debug] proxy_util.c(2029): proxy: HTTP: 
> has
> released connection for (jbosshost)
>
> OS:
>
> RHEL 6.5



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