Re: DNS problem

On Thu, 2006-10-26 at 23:35 +0530, Jegadeesh wrote:

> We checked with dig and we dont see any problem getting the names resolved.
> ... We also tested with iperf and we get the maximum
> bandwidth between the dns and the polyclient. The tcpdump on the dns
> shows the queries and response to and from the server. The dns daemon
> also gets considerable load.

I am guessing the DNS resolution problems are indeed load-related then.
DNS messages are sent using unreliable UDP and are likely to be lost
now-and-then when the load gets high.

> > 1) Hack Polygraph sources to avoid the resolution for all or a
> > hard-coded set of domain names. The response(s) will be hard-coded. This
> > should work fine for a one-time test.
> >
> How about using the library calls like gethostbyname() which can be
> used to get the resolution through hosts files.

Sure, /etc/hosts via gethostbyname() would be better than hard-coded
values, from configuration point of view.

However, since gethostbyname() is blocking, you cannot use it for names
outside /etc/hosts and since gethostbynbame() reads /etc/hosts for every
query, polyclt performance will probably degrade even if all names are
in that file.

Alex.
Received on Thu Oct 26 16:20:46 2006