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www.smugmug.com DNS problem
eyeDutch
Registered Users Posts: 54 Big grins
I can't reach www.smugmug.com and I see why. The problem is that it's a CNAME pointing to hera.smugmug.com which is a CNAME to www.smugmug.com, so it's an endless loop.
; <<>> DiG 9.4.2 <<>> any www.smugmug.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 122
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 1
;; QUESTION SECTION:
;www.smugmug.com. IN ANY
;; ANSWER SECTION:
www.smugmug.com. 759 IN CNAME hera.smugmug.com.
; <<>> DiG 9.4.2 <<>> a hera.smugmug.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 30234
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;hera.smugmug.com. IN A
;; ANSWER SECTION:
hera.smugmug.com. 738 IN CNAME www.smugmug.com.
www.smugmug.com. 738 IN CNAME hera.smugmug.com.
Normally, a CNAME RR points to an A RR, and chaining CNAMEs is not advised, as you could end up with situations like above.
This might be related to http://www.dgrin.com/showthread.php?t=98704
DNS works with cache timeouts so depending on what you have in your local resolver's cache this may work for you or not. Best is to run your own DNS server (I do) on which you can flush the cache by restarting it to find out if things are healthy. The number right after the name of the RR is the amount of seconds of cache timeout left to go.
Please fix, this is preventing me from logging in. -- Paul
; <<>> DiG 9.4.2 <<>> any www.smugmug.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 122
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 1
;; QUESTION SECTION:
;www.smugmug.com. IN ANY
;; ANSWER SECTION:
www.smugmug.com. 759 IN CNAME hera.smugmug.com.
; <<>> DiG 9.4.2 <<>> a hera.smugmug.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 30234
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;hera.smugmug.com. IN A
;; ANSWER SECTION:
hera.smugmug.com. 738 IN CNAME www.smugmug.com.
www.smugmug.com. 738 IN CNAME hera.smugmug.com.
Normally, a CNAME RR points to an A RR, and chaining CNAMEs is not advised, as you could end up with situations like above.
This might be related to http://www.dgrin.com/showthread.php?t=98704
DNS works with cache timeouts so depending on what you have in your local resolver's cache this may work for you or not. Best is to run your own DNS server (I do) on which you can flush the cache by restarting it to find out if things are healthy. The number right after the name of the RR is the amount of seconds of cache timeout left to go.
Please fix, this is preventing me from logging in. -- Paul
0
Comments
I've been doing DNS since 1994, so I understand the badness that can happen with circular CNAMEs. We'd never knowingly create one, and I'm happy to report we didn't this time - but that doesn't mean we didn't blow it.
What actually happened is one of our slaves didn't properly get a DNS zone update while all the others did. So you were getting 'www' results from one server and 'hera' results from another which happened to collide.
Nice catch, and we've resolved the problem. Sorry for all the hassle!
I'm happy you got it sorted, thanks!
-- Paul