DNS FAQs
Here are some questions that customers and evaluators often ask our Technical Support group. If you can't find an answer to your questions here, please contact us.
What resolver does InterMapper OSX use for its DNS?
InterMapper sometimes won't show a device's DNS name...
What resolver does InterMapper OSX use for its DNS?
InterMapper uses two different DNS resolvers. When you add a device using the Add Device... command, InterMapper uses the system's resolver. When InterMapper is monitoring DNS names and addresses as part of the "DNS Check" feature, InterMapper does its own DNS operations, via UDP packets, to the domain name servers listed in InterMapper's own DNS Monitor Preferences panel. InterMapper's built-in domain name resolver currently assumes that the domain name is fully-qualified. For each domain name, the interval for double-checking the domain name is determined by the TTL in each DNS response (with the minimum interval controlled by the DNS Monitor prefs panel).
When you discover devices, InterMapper initially looks up the FQDN name from the IP address (address --> name), then it settles down to monitoring the domain name (name --> address). InterMapper's built-in DNS resolver doesn't handle partially qualified domain names or things that aren't really domain names; hence, they will fail to resolve.
InterMapper sometimes won't show a device's DNS name...
From the Edit menu, you can choose the Set Info submenu, then choose Set Address... to change the DNS option for each affected device from Resolve name to address to Resolve address to name. With this setting InterMapper always resolves the address to a name, and you don't see errors with names that aren't fully-qualified domain names.
What is a FQDN?
This is an acronym for a "Fully-Qualified Domain Name." Within an organization, it's convenient to refer to a computer by the first part of its name, knowing that "everyone" will know that the remainder is the same as the other computers in the organization. Thus, you may speak of "sneezy" and "dopey", knowing that they're really two computers at "seven-dwarves.org".
But computers need the fully written-out name (the FQDN), such as "sneezy.seven-dwarves.org." or "dopey.seven-dwarves.org." to identify a computer. Most user software has the ability to add a "search domain" to all partially-qualified domain names, filling out the missing part of the FQDN. But some DNS servers require the FQDN to work properly with InterMapper. To be safe, it's always correct to enter the full domain name.
Tip: Even though you enter a FQDN when specifying a computer, you can use the Short, Smart Name when constructing a label for a device.
Tip: Technically, a FQDN requires a "." at the end. Just as the search domain is tacked onto the end of a partial domain name, most user software adds the trailing "."