< Previous by Date Date Index Next by Date >
< Previous in Thread Thread Index Next in Thread >

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.

No virus found in this outgoing message.
Checked by AVG Free Edition. 
Version: 7.5.476 / Virus Database: 269.10.8/904 - Release Date: 7/16/2007
5:42 PM