Knowledge Front’s DNS monitor performs a standard DNS query the specified IP address directly. The response is compared to a list of expected results. If the query fails or the results differ an alert is triggered.
Currently A, CNAME, MX, and PTR record types are supported. For explanations of lookup types see Wikipedia: List of DNS record types
Performing reverse lookups is done by using the PTR record type, reversing the octets of the IP address, and appending the special .in-addr.arpa domain. For example to do a reverse lookup on 192.0.2.5 the Query field would be 5.2.0.192.in-addr.arpa.
When Inspect Answer is checked the Answer List is a comma or space separated list of hostnames or IP addresses that are expected to be returned from the given query. MX record tests ignore the priority field, focusing only on the hostnames returned by the query.
Spaces, newlines, and commas are all accepted as separators.
examples:
www1.example.com, www2.example.com1.2.3.4 192.168.5.12