Subject: Re: I-D ACTION:draft-ietf-dnsop-respsize-00.txt

From: "D. J. Bernstein" <[email-masked]>
Date: 3 Jul 2003 22:51:53 -0000

The notion that we're stuck at 13 servers is silly. For example:

   com NS a.gtld-servers.com
   com NS b.gtld-servers.com
   com NS c.gtld-servers.com
   com NS d.gtld-servers.com
   a.gtld-servers.com A ...
   a.gtld-servers.com A ...
   a.gtld-servers.com A ...
   a.gtld-servers.com A ...
   b.gtld-servers.com A ...
   b.gtld-servers.com A ...
   b.gtld-servers.com A ...
   b.gtld-servers.com A ...
   c.gtld-servers.com A ...
   c.gtld-servers.com A ...
   c.gtld-servers.com A ...
   c.gtld-servers.com A ...
   d.gtld-servers.com A ...
   d.gtld-servers.com A ...
   d.gtld-servers.com A ...
   d.gtld-servers.com A ...

Another way to spread the load is to vary the IP addresses.

---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago
#----------------------------------------------------------------------
# To unsubscribe, send a message to <[email-masked]>.

---

From: Rob Austein <[email-masked]>
Date: Thu, 03 Jul 2003 23:12:57 -0400

>    com NS d.gtld-servers.com

This has been suggested before, and it's an appealing idea, but it
assumes that resolvers will try every address of every listed server.
RFC 1035 is, unfortunately, not entirely consistant about this: some
parts of the resolver description talk about putting all of the
addresses of all of the listed name servers into the SLIST, but others
talk about removing a "name server" (as opposed to one its addresses)
from the SLIST.  So there's an open question as to whether a resolver
should treat your example as 16 distinct addresses to try, or should
treat it as four name servers to try; one could find support for
either choice in the spec.
#----------------------------------------------------------------------
# To unsubscribe, send a message to <[email-masked]>.

---

From: "D. J. Bernstein" <[email-masked]>
Date: 4 Jul 2003 15:14:38 -0000

> assumes that resolvers will try every address of every listed server.

No. No widely deployed program tries _every_ address; there are always
limits. But if you try the 4x4 strategy (which still has quite a bit of
room in the UDP packet) then you'll see that the load is spread quite
evenly across 16 servers. The other strategy can't do better than 13.