[98360] in North American Network Operators' Group
Re: large organization nameservers sending icmp packets to dns servers.
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Mon Aug 6 11:59:34 2007
To: Drew Weaver <drew.weaver@thenap.com>
Cc: "'nanog@merit.edu'" <nanog@merit.edu>
In-Reply-To: Your message of "Mon, 06 Aug 2007 11:53:15 EDT."
<B7152C470C9BF3448ED33F16A75D81C14D04152AD7@exchanga.thenap.com>
From: Valdis.Kletnieks@vt.edu
Date: Mon, 06 Aug 2007 11:57:08 -0400
Errors-To: owner-nanog@merit.edu
--==_Exmh_1186415828_9507P
Content-Type: text/plain; charset=us-ascii
On Mon, 06 Aug 2007 11:53:15 EDT, Drew Weaver said:
> Is it a fairly normal practice for large companies such as Yahoo! And
> Mozilla to send icmp/ping packets to DNS servers? If so, why?
Sounds like one of the global-scale load balancers - when you do a (presumably)
recursive DNS lookup of one of their hosts, they'll ping the nameserver from
several locations and see which one gets an answer the fastest.
Yes, it's a semi-borkken strategy, because it assumes that:
1) ICMP is handled at the same rate as TCP/UDP packets in all the routers
involved (so there's no danger of declaring a path "slow" when it really isn't,
just becase a router slow-pathed ICMP).
2) That the actual requester of service is reasonably near net-wise to the
server handling the end-user's recursive DNS lookup.
--==_Exmh_1186415828_9507P
Content-Type: application/pgp-signature
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (GNU/Linux)
Comment: Exmh version 2.5 07/13/2001
iD8DBQFGt0TUcC3lWbTT17ARAoDhAKDabkStfOXPGulHlihVd1tw5W8/kQCeNvSH
ngAEPZjcJ/oluC0NBM8INd0=
=Axgd
-----END PGP SIGNATURE-----
--==_Exmh_1186415828_9507P--
