nanog mailing list archives
Re: Common operational misconceptions
From: Mark Andrews <marka () isc org>
Date: Fri, 17 Feb 2012 01:28:36 +1100
In message <20120216134437.GB65401 () macbook bluepipe net>, Phil Regnauld writes:
Mark Andrews (marka) writes: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 txt9.8.1P1 on a dual stacked native v6 host: I'm seeing TC on both answers, the difference is the TCP answer comes through on v4 but v6 gives SERVFAIL.
You will see TC between dig and the resolver. If you see TC between the resolver and the server it will fail as neither server answers over TCP. If you are seeing TC between the resolver and the server and the TCP query is being answers then something in the path is intercepting the DNS queries.
Don't see any v6 fragments (that'd be a problem since PF doesn't handle them on this host).
You should see something like this on the wire. The second query is to answer dig's query over TCP. 01:19:30.421959 IP6 2001:470:1f00:820:6965:eba7:eff6:1242.64345 > 2001:4f8:0:2::8.53: 44698% [1au] TXT? edns-v6-ok.isc.org. (47) 01:19:30.591828 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (0|1232) 53 > 64345: 44698*- 1/0/1 TXT[|domain] 01:19:30.592851 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (1232|1232) 01:19:30.593889 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (2464|1232) 01:19:30.593963 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (3696|408) 01:19:30.596552 IP6 2001:470:1f00:820:6965:eba7:eff6:1242.61500 > 2001:4f8:0:2::8.53: 60740% [1au] TXT? edns-v6-ok.isc.org. (47) 01:19:30.767351 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (0|1232) 53 > 61500: 60740*- 1/0/1 TXT[|domain] 01:19:30.768362 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (1232|1232) 01:19:30.769399 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (2464|1232) 01:19:30.769473 IP6 2001:4f8:0:2::8 > 2001:470:1f00:820:6965:eba7:eff6:1242: frag (3696|408)
P.
-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka () isc org
Current thread:
- Re: Common operational misconceptions, (continued)
- Re: Common operational misconceptions John Kristoff (Feb 16)
- Re: Common operational misconceptions Tony Tauber (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 15)
- Re: Common operational misconceptions Masataka Ohta (Feb 15)
- Re: Common operational misconceptions Steve Bertrand (Feb 15)
- Re: Common operational misconceptions sthaug (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Jeroen Massar (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Phil Regnauld (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Phil Regnauld (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Daniel Griggs (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Owen DeLong (Feb 15)
- Re: Common operational misconceptions Paul Thornton (Feb 16)
- Re: Common operational misconceptions Jared Mauch (Feb 16)
- Re: Common operational misconceptions Owen DeLong (Feb 16)
- Re: Common operational misconceptions Ray Soucy (Feb 16)
- Re: Common operational misconceptions Jeff Kell (Feb 16)