nested CNAMEs resolution failures?

Mark Andrews marka at isc.org
Mon Jan 29 13:27:43 UTC 2018


Load balancer that punts the answer to the backing server which doesn’t have zone content that is consistent with what is being served by the front end.  In this case the CNAME record is missing from the backing server. 

-- 
Mark Andrews

> On 29 Jan 2018, at 23:42, Tony Finch <dot at dotat.at> wrote:
> 
> cardenas at sig.com <cardenas at sig.com> wrote:
> 
>> Can someone help me understand why I cannot resolve file.caixin.com, but
>> if I direct my queries to open resolvers from the likes of
>> Google/Verizon they yield positive results?
> 
> Good grief, another DNS cookie problem. Weirdly their servers seem to cope
> OK with cookies except for this CNAME - e.g. www.caixin.com works and has
> a similar CNAME, but file.caixin.com fails.
> 
> $ dig +short ns caixin.com | while read s; do dig +short $s a $s aaaa; done
> 43.242.49.158
> 43.242.49.158
> 113.209.232.218
> 
> $ dig file.caixin.com @43.242.49.158
> 
> ; <<>> DiG 9.13.0-dev <<>> file.caixin.com @43.242.49.158
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 33984
> ;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
> ;; WARNING: recursion requested but not available
> 
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags:; udp: 4096
> ;; QUESTION SECTION:
> ;file.caixin.com.               IN      A
> 
> ;; AUTHORITY SECTION:
> caixin.com.             60      IN      SOA     bj.gtm.caijingnews.com. hostmaster.bj.gtm.caijingnews.com. 2373 10800 3600 604800 60
> 
> ;; Query time: 184 msec
> ;; SERVER: 43.242.49.158#53(43.242.49.158)
> ;; WHEN: Mon Jan 29 12:38:04 GMT 2018
> ;; MSG SIZE  rcvd: 110
> 
> $ dig +nocookie file.caixin.com @43.242.49.158
> 
> ; <<>> DiG 9.13.0-dev <<>> +nocookie file.caixin.com @43.242.49.158
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36216
> ;; flags: qr aa rd ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
> ;; WARNING: recursion requested but not available
> 
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags:; udp: 4096
> ;; QUESTION SECTION:
> ;file.caixin.com.               IN      A
> 
> ;; ANSWER SECTION:
> file.caixin.com.        3600    IN      CNAME   www.caixin.com.bbdglb.com.
> 
> ;; Query time: 182 msec
> ;; SERVER: 43.242.49.158#53(43.242.49.158)
> ;; WHEN: Mon Jan 29 12:38:21 GMT 2018
> ;; MSG SIZE  rcvd: 80
> 
> Tony.
> -- 
> f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/  -  I xn--zr8h punycode
> Viking, North Utsire, South Utsire: Northwesterly 6 to gale 8, backing
> westerly 5 to 7 later. Rough or very rough. Showers. Good.
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