16 Feb
2012
16 Feb
'12
7:01 a.m.
If you want to know if your resolver talks IPv6 to the world and supports 4096 EDNS UDP messages the following query will tell you.
dig edns-v6-ok.isc.org txt
Similarly for IPv4.
dig edns-v4-ok.isc.org txt
Both PowerDNS recursor 3.3 and Nominum CNS 3.0.5 have problems with these queries. They both get the TC answer from 149.20.64.58 / 2001:4f8:0:2::8. Then: - CNS tries with 4000 EDNS UDP size (4000 is the CNS documented max UDP size), gets another TC. - PowerDNS doesn't try to used EDNS at all. Then they both try TCP and get a RST. And then they return SERVFAIL. Steinar Haug, Nethelp consulting, sthaug@nethelp.no