[dns-operations] Can a 1s TTL cause weird failures?

[Mark Andrews]

> I'm having a problem with some of my servers in the SF Bay Area not 
> being able to look up the MX record for the zone "weckerphoto.co.uk.". 
> Below is a complete tcpdump record of the packets that go back and forth 
> during the attempt.
> 
> I'm logged into my recursive DNS server.
> 
> [r0-66:~]$ dig @127.0.0.1 weckerphoto.co.uk. mx
> 
> ; <<>> DiG 8.3 <<>> @127.0.0.1 weckerphoto.co.uk. mx
> ; (1 server found)
> ;; res options: init recurs defnam dnsrch
> 19:48:48.402533 66.218.66.112.33701 > 212.121.40.130.53:  55962 [1au] A? 
> dns03.1stdomains.co.uk. (51)
> 19:48:48.402585 66.218.66.112.33701 > 212.121.40.130.53:  42665 [1au] A? 
> ns03.1stdomains.co.uk. (50)
> 19:48:48.402627 66.218.66.112.33701 > 212.121.40.130.53:  24761 [1au] 
> MX? weckerphoto.co.uk. (46)
> 19:48:48.568601 212.121.40.130.53 > 66.218.66.112.33701:  55962- 0/2/3 
> (131) (DF)
> 19:48:48.568761 212.121.40.130.53 > 66.218.66.112.33701:  42665- 0/2/3 
> (130) (DF)
> 19:48:48.568771 212.121.40.130.53 > 66.218.66.112.33701:  24761- 0/2/1 
> (96) (DF)
> 19:48:48.568799 66.218.66.112.33701 > 81.19.63.101.53:  6345 [1au] A? 
> dns03.1stdomains.co.uk. (51)
> 19:48:48.568849 66.218.66.112.33701 > 81.19.63.101.53:  6356 [1au] A? 
> ns03.1stdomains.co.uk. (50)
> 19:48:48.716361 81.19.63.101.53 > 66.218.66.112.33701:  6345*- 1/2/3 A 
> 81.19.63.150 (147) (DF)
> 19:48:48.716508 81.19.63.101.53 > 66.218.66.112.33701:  6356*- 1/2/3 A 
> 81.19.63.151 (146) (DF)
> 19:48:53.406873 66.218.66.112.33701 > 204.74.113.44.53:  39173 [1au] A? 
> dns03.1stdomains.co.uk. (51)
> 19:48:53.406919 66.218.66.112.33701 > 204.74.113.44.53:  48393 [1au] A? 
> ns03.1stdomains.co.uk. (50)
> 19:48:53.406961 66.218.66.112.33701 > 204.74.113.44.53:  20944 [1au] MX? 
> weckerphoto.co.uk. (46)
> 19:48:53.411291 204.74.113.44.53 > 66.218.66.112.33701:  20944- 0/2/1 
> (96) (DF)
> 19:48:53.412023 204.74.113.44.53 > 66.218.66.112.33701:  39173- 0/2/3 
> (131) (DF)
> 19:48:53.412029 204.74.113.44.53 > 66.218.66.112.33701:  48393- 0/2/3 
> (130) (DF)
> 19:48:53.412122 66.218.66.112.33701 > 88.208.202.90.53:  58020 [1au] A? 
> dns03.1stdomains.co.uk. (51)
> 19:48:53.412173 66.218.66.112.33701 > 88.208.202.90.53:  26171 [1au] A? 
> ns03.1stdomains.co.uk. (50)
> 19:48:53.573975 88.208.202.90.53 > 66.218.66.112.33701:  58020*- 1/2/3 A 
> 81.19.63.150 (147) (DF)
> 19:48:53.573982 88.208.202.90.53 > 66.218.66.112.33701:  26171*- 1/2/3 A 
> 81.19.63.151 (146) (DF)
> ;; res_nsend: Operation timed out
> [r0-66:~]$
> 
> You might notice that it immediately issues three queries.  Two are for 
> the A records of weckerphoto's authoritative servers.  In addition, it 
> asks one of the co.uk. auth servers for the MX record.  It gets 
> referrals back from all three queries.
> 
> Then it asks 1stdomains.co.uk.'s auth servers for the A records for 
> "{d,}ns03.1stdomains.co.uk.".  It gets a response back, and then just 
> hangs; no further action occurs.
> 
> Note particularly that even though it finds out what the A record for 
> {d,}ns03.1stdomains.co.uk are, it never queries them about 
> weckerphoto.co.uk.
> 
> My suspicion is that this is happening because the TTL on the A records 
> for {d,}ns03.1stdomains.co.uk is extremely low:
> 
> ;; ANSWER SECTION:
> dns03.1stdomains.co.uk.  1S IN A  81.19.63.150
> 
> ;; ANSWER SECTION:
> ns03.1stdomains.co.uk.  1S IN A         81.19.63.151
> 
> My nameserver is BIND 8.4.6.

	BIND 8 doesn't have query restart.  Upgrade.
 
> Does anyone have any ideas on what might be going on here?
> 
> Mark K. Pettit
> pettit at yahoo-inc.com
> DNS Administrator
> Yahoo!, Inc.
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org