nanog mailing list archives
Re: Google DNS Oddity
From: Warren Kumari <warren () kumari net>
Date: Mon, 9 Sep 2019 14:32:22 -0400
Yes, this is no longer occurring / is resolved. Apologies, W On Mon, Sep 9, 2019 at 1:37 PM Florian Brandstetter via NANOG < nanog () nanog org> wrote:
Unable to replicate this in London: ``` ; <<>> DiG 9.11.5-P1-1ubuntu2.5-Ubuntu <<>> @ns1.google.com. www.google.com. aaaa ; (2 servers found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61970 ;; 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: 512 ;; QUESTION SECTION: ;www.google.com. IN AAAA ;; ANSWER SECTION: www.google.com. 300 IN AAAA 2a00:1450:4009:80d::2004 ``` going by the latency, ns1.google.com <https://link.getmailspring.com/link/C27D5EBE-B680-425A-B057-218C6300A7B4 () getmailspring com/0?redirect=ns1.google.com&recipient=bmFub2dAbmFub2cub3Jn> travels to NL from our UK PoPs though: ``` Host Loss% Snt Last Avg Best Wrst StDev 1. ??? 2. ??? 3. ae26-0.ebr01.lon3.uk.globalone 0.0% 13 2.1 6.2 1.0 45.7 12.9 4. 2001:7f8:4::3b41:1 0.0% 13 0.7 0.8 0.6 1.7 0.4 5. 2001:4860:0:1101::10 0.0% 13 0.7 2.7 0.7 14.2 4.2 6. 2001:4860::c:4000:cf5b 0.0% 13 1.8 2.1 1.5 4.0 0.7 7. 2001:4860::8:4000:d325 0.0% 13 8.6 7.3 6.6 9.5 0.9 8. 2001:4860::22:4001:70b 0.0% 13 6.4 9.5 6.4 36.9 8.3 9. 2001:4860:0:1::be7 23.1% 13 7.3 7.5 7.3 7.7 0.1 10. ??? 11. ??? 12. ??? 13. ??? 14. ??? 15. ??? 16. ??? 17. ??? 18. ??? 19. ns1.google.com 0.0% 12 6.4 6.4 6.3 6.5 0.0 ``` On Sep. 6 2019, at 9:49 pm, Stephen Stuart <stuart () tech org> wrote: Do you see the same behavior when you execute your dig query without the trailing dot? Thanks, Stephen On Sep 6, 2019, at 3:11 PM, Chip Marshall via NANOG <nanog () nanog org> wrote: Hello, I'm seeing an oddity when doing DNS lookups for www.google.com from our London datacenter, and I'm curious if other people are seeing the same behavior. It appears that when we ask for www.google.com. we sometimes get an answer that only contains records for www-anycast.google.com., which our resolver ignores as they don't match the query. As seen with dig: ``` # dig @ns1.google.com. www.google.com. aaaa ; <<>> DiG 9.10.3-P4-Ubuntu <<>> @ns1.google.com. www.google.com. aaaa ; (2 servers found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42641 ;; flags: qr aa rd; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;www.google.com. IN AAAA ;; ANSWER SECTION: www-anycast.google.com. 300 IN AAAA 2001:4860:4802:34::75 www-anycast.google.com. 300 IN AAAA 2001:4860:4802:38::75 www-anycast.google.com. 300 IN AAAA 2001:4860:4802:36::75 www-anycast.google.com. 300 IN AAAA 2001:4860:4802:32::75 ;; Query time: 7 msec ;; SERVER: 216.239.32.10#53(216.239.32.10) ;; WHEN: Fri Sep 06 19:05:32 UTC 2019 ;; MSG SIZE rcvd: 167 ``` So far I've observed this with A and AAAA queries. It's my understanding that without a CNAME record in the answer, the resolver is doing the right thing by ignoring the answer, as there's no linkage between www and www-anycast. Is this broken, or is this just some weird DNS trick I've not come across before? You may want to post on dns-operations instead. Can you do a dig +trace www.google.com instead, that would be more instructive about whatт€™s happening at each layer o f the delegation. - Jared [image: Sent from Mailspring]
-- I don't think the execution is relevant when it was obviously a bad idea in the first place. This is like putting rabid weasels in your pants, and later expressing regret at having chosen those particular rabid weasels and that pair of pants. ---maf
Current thread:
- Google DNS Oddity Chip Marshall via NANOG (Sep 06)
- Re: Google DNS Oddity Jared Mauch (Sep 06)
- Re: Google DNS Oddity Stephen Stuart (Sep 06)
- Re: Google DNS Oddity Chip Marshall via NANOG (Sep 06)
- Re: Google DNS Oddity Florian Brandstetter via NANOG (Sep 09)
- Re: Google DNS Oddity Warren Kumari (Sep 09)
- Re: Google DNS Oddity Stephen Stuart (Sep 06)
- Re: Google DNS Oddity Chip Marshall via NANOG (Sep 06)
- Re: Google DNS Oddity Jared Mauch (Sep 06)
- Re: Google DNS Oddity Nick Hilliard (Sep 06)
- Re: Google DNS Oddity Nick Hilliard (Sep 06)
- Re: Google DNS Oddity Florian Brandstetter via NANOG (Sep 09)
- Re: Google DNS Oddity Nick Hilliard (Sep 06)