-----Original Message-----
From: Karyn Ulriksen [mailto:valkaryn@valkaryn.net]
Sent: Monday, January 21, 2002 8:39 AM
To: James Smith
Subject: RE: DNS DOS increasing?

I've seen this behavior before, also.  I thought it was interesting that two servers side by side recieving the same attacks/ratios only serving DNS (BIND 8.2.x*) and  acted in this manner:

 

        Redhat 6.2 w/dual proc 833 512/ram    started "loosing" RR records

        Solaris 7 on a Sparc 10 (hehe) w/256    rebooted and served the correct records

 

I'm curious to see how other OSes react to these attacks.  My guess is that BSD systems (such as FreeBSD and BSDi) will react similarly to the Solaris based on my past experience with these systems.  So I am curious too see if the RR record "loss" is an OS specific behaviour, especially since Redhat has priors in misplacing information in earlier versions of the OS.

 

* I say BIND 8.2.x, because this continued to occur through the various BIND 8.2 releases.

 

Best regards,

Karyn Ulriksen
Valkaryn Internet Group
URL: http://www.valkaryn.net
email:  valkaryn@valkaryn.net
===========================================
"Decisions should be made in the space of seven breaths."

-----Original Message-----
From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of James Smith
Sent: Monday, January 21, 2002 7:08 AM
To: nanog@merit.edu
Subject: RE: DNS DOS increasing?

 I've seen DOS-type behavior where a client will query a resolver for a
 name that doesn't exist, and the client does not accept the answer that
 the name does not exist and immediately sends another query, regardless
 of whether or not the resolver declared itself authoritative for the
 negative answer.

--
/ak

  Get ready for more DOS-like behavior as systems get deployed that have 10 second TTLs in the DNS. These systems are used to provide multi-isp redundancy by pinging each upstreams router, and when a ping fails, start giving out a dns response using the other ISP IP range. Same FQDN, new IP.

  This of course is driven by the desire for redundancy in small businesses who make the Internet an integral part of their business plan. Either they can't get PI space and don't have (or don't want to spend) the $$$ to do BGP, or are unable to convince their upstream to cut a hole in their CIDR block and allow a 2nd party to announce that chunk (which for some is as small as /28).

James H. Smith II  NNCDS NNCSE
Systems Engineer
The Presidio Corporation