The DNS service is indeed built into the core of the network (for the time being - see my Petname System pull request). The only thing “on top” of the network that MaidSafe (the company) has planned to build so far is “LiteStuff” -the dropbox replacement. Everything else that is in their repo is for the core of the network itself[1].
[1] Except for QA - that is their internal droplet setup repo for testing the network on the servers that they are renting while they build it.