Seems like dig doesn't always advertise a big enough buffer, I was having the same issue as you. If you set the buffer size on the command line it works as directed.
Daniels-Mac-mini:~ daniel$ dig edns-v4-ok.isc.org txt @149.20.64.58 ;; Truncated, retrying in TCP mode. ;; Connection to 149.20.64.58#53(149.20.64.58) for edns-v4-ok.isc.orgfailed: connection refused. Daniels-Mac-mini:~ daniel$ dig edns-v4-ok.isc.org txt @149.20.64.58+bufsize=4096 ; <<>> DiG 9.7.3-P3 <<>> edns-v4-ok.isc.org txt @149.20.64.58 +bufsize=4096 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18209 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;edns-v4-ok.isc.org. IN TXT ;; ANSWER SECTION: edns-v4-ok.isc.org. 0 IN TXT "EDNS-4096-OK" "EDNS-4096-OK" "EDNS-4096-OK" "EDNS-4096-OK" "EDNS-4096-OK" "EDNS-4096-OK" <snip> "EDNS-4" ;; Query time: 176 msec ;; SERVER: 149.20.64.58#53(149.20.64.58) ;; WHEN: Fri Feb 17 10:22:08 2012 ;; MSG SIZE rcvd: 4096 On 17 February 2012 05:53, Phil Regnauld <regna...@nsrc.org> wrote: > Borderline dns-ops, sorry folks! - but this is interesting > as we've been talking about ipv6 being operational, and this > is part of it... > > Mark Andrews (marka) writes: > > > > 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. > > TC is on the answer from the remote server to my resolver, so > yeah, seems > like something is messing with the packets. > > > > 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. > > I'm not seeing fragments as you are. > > Here's what I see: > > 14:40:20.955876 IP6 2001:2000:1080:d::2.64561 > 2001:4f8:0:2::8.53: 52841 > TXT? edns-v6-ok.isc.org. (36) > 14:40:21.141948 IP6 2001:4f8:0:2::8.53 > 2001:2000:1080:d::2.64561: > 52841*-| 0/0/0 (36) > 14:40:21.142259 IP6 2001:2000:1080:d::2.53262 > 2001:4f8:0:2::8.53: Flags > [S], seq 1112939462, win 65535, options [mss 1440,nop,wscale 6,sackOK,TS > val 2571957531 ecr 0], length 0 > 14:40:21.327895 IP6 2001:4f8:0:2::8.53 > 2001:2000:1080:d::2.53262: Flags > [R.], seq 0, ack 1112939463, win 0, length 0 > > Cheers, > Phil > > -- Daniel Griggs Network Operations e: dan...@fx.net.nz d: +64 4 4989567