I've searched on google in the last hour and couldn't find anything relevant to my issue, I have bind installed and running flawlessly which I'm using for multiple domains and local reverse lookups, still ... some remote nameservers are offline and do not return any result to my requests, and that's slowing the applications which are using bind.
For example:
# dig @127.0.0.1 -x 155.1.2.3
; <<>> DiG 9.9.5-9+deb8u8-Debian <<>> @127.0.0.1 -x 155.1.2.3
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 40057
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;3.2.1.155.in-addr.arpa. IN PTR
;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Tue Dec 27 14:06:14 EET 2016
;; MSG SIZE rcvd: 51
timeouts after ~ 5 seconds, but if I retry the command the result (SERVFAIL) isn't cached and my application is delayed for another 5 seconds over and over again. I know that I can implement caching inside the application but I'm sure it will be alot more efficient to create caches for this within bind configuration.
How can I cache SERVFAIL for ... let's say 5 minutes ? It's supported by bind ?
Thank you!
By default bind caches all the responses. what is the TTL you are receiving in the SERVFAIL response? Also check if you have max-ncache-ttl set to 0 on the client resolver configuration.