dns_check advice needed regarding cached results
Posted: Tue Sep 02, 2014 1:10 pm
Hi,
I have been using Nagios for a while and it seems to be working fine.
However, I just ran into an issue with check_dns passing a DNS server due to a cached result. It seems to me that if DNS_check is always checking the same resolvable host, the DNS server will return a result from its cache (until expiry). So although this server couldn't resolve anything else due to a failure with its forwarders, Nagios reports all is OK.
My interest in the checking DNS is for basic server functionality and not about any particulars on a specific host.
I have been looking into the +norecurse feature of dig, but find that some DNS refuse queries with this option.
I welcome suggestions as to how to best determine if a DNS server is really working or not.
Thanks in advance.
Mike
I have been using Nagios for a while and it seems to be working fine.
However, I just ran into an issue with check_dns passing a DNS server due to a cached result. It seems to me that if DNS_check is always checking the same resolvable host, the DNS server will return a result from its cache (until expiry). So although this server couldn't resolve anything else due to a failure with its forwarders, Nagios reports all is OK.
My interest in the checking DNS is for basic server functionality and not about any particulars on a specific host.
I have been looking into the +norecurse feature of dig, but find that some DNS refuse queries with this option.
I welcome suggestions as to how to best determine if a DNS server is really working or not.
Thanks in advance.
Mike