fcl-net
From Free Pascal wiki
fcl-net is a package of the FCL that provides networking services, including the former netdb - DNS resolving
While this package is used (witnessed by a steady flow of bugreports), the progress is relatively slow, and the code a bit old.
It would already help tremendously if knowledgable users would contribute a few decent demoes. (that could also be used to test certain functionality)
Since many people had a problem with DNS resolving under *nix, a header translation roughly equivalent to POSIX libresolv functionality has been added in 2.4.4 for FreeBSD and Linux.
Example code is available in /usr/local/share/fpcsrc/packages/fcl-net/examples.