IDM TEST wrote:
> We are currently running the BIND 9.3.2-P2 on our DNS servers (caching servers) and everything is working fine. If we upgrade to the version to (bind 9.5.0 - P2), we face many DNS resolving problems described by "Server Failed" messages on NSLOOKUP query (for any domain)

I'd immediately recommend that you set max-cache-size to a reasonable
value and see if it cures the problem.