I was getting error (network unreachable) resolving messages in my bind log.
After investigation this appears to be due to IPv6 addresses. Do you use IPv6 on your server? If not, you can instruct BIND to only use IPv4 by adding the option “-4” to its startup parameters.
My server is CENTOS based and I use Virtualmin / Webmin for admin, and there is no option in Webmin / BIND for this so needed to investigate further.
The file to edit is /etc/sysconfig/named and the line to add is
obviously then restart BIND (service named restart or use Webmin)
On Debian/Ubuntu, those are located in the file /etc/default/bind9.