Re: forward and reverse dns lookups (not linux related)

DNS/RDNS should* be using udp. Port 53 tcp is for bulk operations like
zone transfers. My firewall permits port 53 UDP from outside, but not
port 53 tcp, since all the zone transfers are intranet.

Actually, I had to put a throttle on port 53 UDP external inbound
traffic as well, since in recent months I've seen several instances of
being DDOS'ed because I was being exploited for DNS reflection attacks.

   Tim

*Unless they aren't.

On Fri, 2012-11-09 at 16:20 -0500, The Donald Cowart wrote:
> Just off the top of my head, one is using TCP, the other UDP???
> 
> --DC
> 
> 
> On Fri, Nov 9, 2012 at 4:17 PM, Robert Mckennon <[email protected]>wrote:
> 
> > So...the issue is:
> >
> > Connected to the coorporate network via a vpn connection through our
> > new cisco ASA, for some reason Forward DNS queries fail, but Reverse
> > DNS queries work....  This is very baffling!
> >
> > I just can't image that the fire somehow is blocking forward lookups
> > but allowing reverse lookups, when icmp and filesharing all work (at
> > least via ip address).
> >
> >
> > Any thoughts???
> >
> > Rob.
> >
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