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