-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 There are other known examples. One that springs to mind is:
www.microsoft.com. 3063 IN CNAME toggle.www.ms.akadns.net. toggle.www.ms.akadns.net. 58 IN CNAME g.www.ms.akadns.net. g.www.ms.akadns.net. 58 IN CNAME lb1.www.ms.akadns.net. lb1.www.ms.akadns.net. 58 IN A 65.55.11.222 lb1.www.ms.akadns.net. 58 IN A 207.46.19.190 lb1.www.ms.akadns.net. 58 IN A 207.46.19.254 lb1.www.ms.akadns.net. 58 IN A 207.46.193.254 lb1.www.ms.akadns.net. 58 IN A 65.55.21.250 lb1.www.ms.akadns.net. 58 IN A 207.46.192.254 However, this is still only two main lookup chains, instead of three like www.yahoo.com.ar. I count around 8 lookups (minimum) to get this answer when starting with an empty cache. I would be more inclined to suspect network connectivity problems with the lookup you're having problems with. With that many lookups, each one needs to complete in a reasonable amount of time - 50 ms on average, or thereabouts, to complete the whole thing in 5 seconds. How is your connection to the various servers involved? These are the servers authoritative for: . ar. com.ar. yahoo.com.ar. com. yahoo.com. g1.b.yahoo.com. a1.b.yahoo.com. Note that yahoo.com.ar and yahoo.com are served by the same servers. Also, the last item is hosted on a subset of the same servers as the next-to-last item. Chris Buxton Professional Services Men & Mice On Sep 4, 2008, at 4:54 AM, caio wrote: > Chris Buxton escribió: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> That still sounds like a performance problem, as Kevin hinted. >> >> In this case, the qname is an alias of an alias (bad, but not >> uncommon), >> and all three names are in different zones. >> >> www.yahoo.com.ar. 1800 IN CNAME hp2.latam.g1.b.yahoo.com. >> hp2.latam.g1.b.yahoo.com. 300 IN CNAME >> us.hp2.latam.a1.b.yahoo.com. >> us.hp2.latam.a1.b.yahoo.com. 300 IN A 98.136.43.19 >> >> That's at least 9 queries if the cache is empty at the beginning, >> more >> if the resolver is verifying glue records. >> >> What happens if you try the query again a few seconds later? >> > > that's the point Chris. > ramdomly the query is resolved OK, and doing nothing, after a while > again the query start to fails... > I could only discover the fail with that qname. > just to test, do you know about another similar qname? which has > many cname? > > -- > caio > > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (Darwin) iEYEARECAAYFAki/8pIACgkQ0p/8Jp6Boi2NBgCfXD7sgbydnBbAb/vk6oaa0S+N 6DcAn25rbZ1dVtWVhe4jkhS3EHIvcQEt =sn6l -----END PGP SIGNATURE-----
