[dns-operations] imdb.com (i.media-imdb.com (iwi.media-imdb.com))

bert hubert bert.hubert at netherlabs.nl
Mon Mar 7 21:04:10 UTC 2011

On Mon, Mar 07, 2011 at 03:46:38PM -0500, Bob Paolucci wrote:
> i.media-imdb.com (iwi.media-imdb.com)

i.media-imdb.com.	180	IN	CNAME	iwi.media-imdb.com.
iwi.media-imdb.com.	60	IN	CNAME	iai.media-imdb.com.
iai.media-imdb.com.	10800	IN	CNAME	i.imdb.com.edgesuite.net.
i.imdb.com.edgesuite.net. 900	IN	CNAME	a1969.g.akamai.net.
a1969.g.akamai.net.	20	IN	A
a1969.g.akamai.net.	20	IN	A

Wow. From a cold cache the PowerDNS Recursor needs *24-26 packets* to
resolve this chain (and it is known to be reasonably thrifty in this

I don't see anything particularly odd, except for the length of this CNAME
chain.  It may be that the 20 second and 60 second TTLs cause some
'resonance' for some resolvers.

The chain is very long though.

> Could this come down to the CNAME being at the zone apex
> Could have something to do with the resolver we're using not liking
> that.

Perhaps your resolver vendor could be of assistance?


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