Sometimes (quite often) I'm unable to access hosts in web browsers. It just happened with http://stats02.syd07.bulletproof.net/ . Ping agrees with Chrome and Firefox that the hostname is unknown:
jesse@Limiting-Factor ~ $ ping stats02.syd07.bulletproof.net
ping: cannot resolve stats02.syd07.bulletproof.net: Unknown host
But using the host command I can do a dns lookup on it just fine:
jesse@Limiting-Factor ~ $ host stats02.syd07.bulletproof.net
stats02.syd07.bulletproof.net is an alias for bpsyd07-pmdh-collectd-02.inf.bulletproof.net.
bpsyd07-pmdh-collectd-02.inf.bulletproof.net has address 10.254.16.62
Host bpsyd07-pmdh-collectd-02.inf.bulletproof.net not found: 3(NXDOMAIN)
Host bpsyd07-pmdh-collectd-02.inf.bulletproof.net not found: 3(NXDOMAIN)
(host verbose output is below).
This generally seems to be a transient problem. It'll look like this for 30 seconds or a minute and then it will magically start resolving for ping and web browsers. Something screwy is happening in Yosemite's name resolution systems....
$ host -v stats02.syd07.bulletproof.net
Trying "stats02.syd07.bulletproof.net"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14883
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 2
;; QUESTION SECTION:
;stats02.syd07.bulletproof.net. IN A
;; ANSWER SECTION:
stats02.syd07.bulletproof.net. 273 IN CNAME bpsyd07-pmdh-collectd-02.inf.bulletproof.net.
bpsyd07-pmdh-collectd-02.inf.bulletproof.net. 273 IN A 10.254.16.62
;; AUTHORITY SECTION:
inf.bulletproof.net. 0 IN NS ns0.bulletproof.net.au.
inf.bulletproof.net. 0 IN NS ns1.bulletproof.net.au.
;; ADDITIONAL SECTION:
ns0.bulletproof.net.au. 21 IN A 202.44.98.24
ns1.bulletproof.net.au. 59 IN A 64.71.152.56
Received 192 bytes from 192.168.178.1#53 in 3 ms
Trying "bpsyd07-pmdh-collectd-02.inf.bulletproof.net"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45169
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;bpsyd07-pmdh-collectd-02.inf.bulletproof.net. IN AAAA
;; AUTHORITY SECTION:
inf.bulletproof.net. 300 IN SOA ns0.bulletproof.net.au. hostmaster.bulletproof.net.au. 2015042400 10800 3600 604800 600
Received 131 bytes from 192.168.178.1#53 in 45 ms
Trying "bpsyd07-pmdh-collectd-02.inf.bulletproof.net"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19315
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;bpsyd07-pmdh-collectd-02.inf.bulletproof.net. IN MX
;; AUTHORITY SECTION:
inf.bulletproof.net. 300 IN SOA ns0.bulletproof.net.au. hostmaster.bulletproof.net.au. 2015042400 10800 3600 604800 600
Received 131 bytes from 192.168.178.1#53 in 45 ms
I'm having some success with killing discoveryd when I start getting this problem at lot.
sudo pkill -f 'discoveryd '