Re: [reSIProcate] ares doesn't send query to DNS servers of othersubnets
> -----Original Message-----
> From: Scott Godin [mailto:slgodin@xxxxxxxxxxxx]
> Sent: Tuesday, July 17, 2007 6:40 AM
> To: Van C. Nguyen; resiprocate-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: RE: [reSIProcate] ares doesn't send query to DNS
> servers of othersubnets
>
> > 3) "why the subnet is equal ..."
> >
> > From the DNS server IP, one can lookup the routing table to see the
> NIC
> > that
> > would be used. Resip already does this to populate the Via.
> From that
> > adapter one gets the network mask. The network mask may be
> applied to
> > either the DNS server IP or NIC IP to get the subnet
> address. With a
> > mask of 255.255.255.0, the subnet IP would be
> 192.168.5.0/24. The IP
> > for the adapter may also be used, if it's simpler.
>
>
> DNS server(s) are not always in the same subnet as the IP
> Address for the NIC.
> What if a particular DNS server is reachable from 2 different
> NICs in the box? (ie. a public DNS server)
We just want to resolve a name (routing is a separate, unrelated process).
If two networks have the *same* DNS servers (same IPs) servicing them, then
they will return the same results, so no harm. It would be a bit more
efficient to remove duplicate DNS servers from the servers list: no sense in
trying the exact DNS server again if the last query timed out. I will make a
note to check this and remove duplicates.
Van.
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5:42 PM