I'll see if I can get a chance to do some packet captures later this week, however, I did notice something that may be relevant.
The domains that seem to fail do not have IPV6 look addresses. The domains that succeed have IPV6 address returns: vagrant@ubuntu-bionic:~$ nslookup google.com Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: google.com Address: 172.217.12.14 Name: google.com Address: 2607:f8b0:400f:805::200e vagrant@ubuntu-bionic:~$ nslookup yahoo.com Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: yahoo.com Address: 98.138.219.231 Name: yahoo.com Address: 98.137.246.7 Name: yahoo.com Address: 98.137.246.8 Name: yahoo.com Address: 72.30.35.9 Name: yahoo.com Address: 72.30.35.10 Name: yahoo.com Address: 98.138.219.232 Name: yahoo.com Address: 2001:4998:44:41d::4 Name: yahoo.com Address: 2001:4998:58:1836::11 Name: yahoo.com Address: 2001:4998:c:1023::4 Name: yahoo.com Address: 2001:4998:c:1023::5 Name: yahoo.com Address: 2001:4998:44:41d::3 Name: yahoo.com Address: 2001:4998:58:1836::10 However, the servers that fail are not returning IPV6 information: vagrant@ubuntu-bionic:~$ nslookup ubuntu.com Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: ubuntu.com Address: 91.189.94.40 ** server can't find ubuntu.com: SERVFAIL vagrant@ubuntu-bionic:~$ nslookup oracle.com Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: oracle.com Address: 137.254.120.50 ** server can't find oracle.com: SERVFAIL vagrant@ubuntu-bionic:~$ nslookup amazon.com Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: amazon.com Address: 176.32.103.205 Name: amazon.com Address: 176.32.98.166 Name: amazon.com Address: 205.251.242.103 ** server can't find amazon.com: SERVFAIL There's also a pause after the last "Address" output line and the "** server" line, where the IPV6 address would be. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1787739 Title: postfix name lookup failed after dist-upgrade (Aug-2018) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bind9/+bug/1787739/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
