I've been running my own name servers (bind9) for many years in Linux boxes, and I have several in my office served by Verizon FiOS. This morning I discovered that I could no longer resolve anything in the google.com domain. Other domain lookups continued to work. I verified that my root server tables are current.
Unable to identify a misconfiguration, and noticing the problem did not exist with a name server in a VPS on a Linode, I tried a work-around. That VPS is on a layer 2 VPN with my office network, so I switched my default route on some of the affected office systems such that all traffic to the Internet went through the VPS. After this switch, name service is OK, resolving google.com.
See demo below. Note that 192.168.10.87 is one of my internal routers that does NAT to the Version FiOS interface. 192.168.10.78 is functioning as a router on the VPN at a remote site, effectively providing a tunnel for my named processes (and everything else unfortunately) to get to the Internet after I change the default route. The behavior is consistent on three separate computers.
I have some half-baked theories about what is going on, but I can't decide how to diagnose this further.
root@flipper:~# host google.com ;; connection timed out; no servers could be reached root@flipper:~# host yahoo.com yahoo.com has address 126.96.36.199 yahoo.com has address 188.8.131.52 yahoo.com has address 184.108.40.206 yahoo.com has IPv6 address 2001:4998:44:204::a7 yahoo.com has IPv6 address 2001:4998:c:a06::2:4008 yahoo.com has IPv6 address 2001:4998:58:c02::a9 yahoo.com mail is handled by 1 mta5.am0.yahoodns.net. yahoo.com mail is handled by 1 mta7.am0.yahoodns.net. yahoo.com mail is handled by 1 mta6.am0.yahoodns.net. root@flipper:~# ip ro del default via 192.168.10.87 root@flipper:~# ip ro add default via 192.168.10.78 root@flipper:~# host google.com google.com has address 220.127.116.11 google.com has IPv6 address 2607:f8b0:4006:80e::200e google.com mail is handled by 30 alt2.aspmx.l.google.com. google.com mail is handled by 40 alt3.aspmx.l.google.com. google.com mail is handled by 10 aspmx.l.google.com. google.com mail is handled by 20 alt1.aspmx.l.google.com. google.com mail is handled by 50 alt4.aspmx.l.google.com. root@flipper:~# cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 127.0.0.1