This hardly seems like something you'd need to write yourself; I'll bet there are programs out there that can already do this.
If you do want to write your own name server, though, start with RFCs 1034 and 1035.
This hardly seems like something you'd need to write yourself; I'll bet there are programs out there that can already do this.
If you do want to write your own name server, though, start with RFCs 1034 and 1035.