AAAA/A6 lookups

Mark_Andrews at Mark_Andrews at
Tue Jan 7 21:05:29 UTC 2003

> All,
> 	I was going through query logs and I notice a couple things that
> maybe one could help. 
> is one of two name servers.
> I see 45,000 requests in a 24 hour period. Of those 45,000 requests only 500
> are A records the rest our AAAA or A6.
> So my questions are 
> 1) Why so many ipv6 requests?

	Because nameservers are looking up missing glue when handing out
	answers and / or they are looking up the address to be able to
	answer a query.

	89 to 1 is not bad considering you have a 1 week TTL for the A
	records and a 1 hour ttl on the negative response.

	There is also a bug in some BIND 8 releases which prevents the
	nameserver seeing the cached negative responses resulting in a
	glue lookup on every response returned to the client.

> 2) Is there any way to black whole these requests? Like maybe creating 
> 	false A6 records with a high TTL ?

	Get yourself IPv6 connected and give the nameservers IPv6
	addresses.  Note you can tunnel in the IPv6 connections
	over a IPv4 net if your upstream does not yet support IPv6.

> 3) Does bind , by default , make A6 queries before ipv4 requests?

	BIND 9 does if the nameserver host OS is IPv6 capable (which
	most are these days).

Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at

More information about the bind-users mailing list