Optimizing DNS Server Selection

In DNS zone delegation, the NS resource records of the delegated domain appear in both the parent and child zones, which complicates the domain name resolution procedure especially for server selection. In this paper, we investigate the recursive resolution mechanism for the delegated domain and the necessary operations. As there are no specifications for such resolution, we provide some recommendations such as NS record substitution mechanism. Furthermore, we analyze the delegation impacts on server selection as the NS records are obtained from both parent and child zone. We propose an integrated sever selection procedure to handle the lame delegation and enhance server selection efficiency. It makes use of the two stages of server probing information and can help save the initial server probing in the server selection algorithm. Several proposals as to the disposal of NS resource records and the maintenance of the rtt information of servers are also presented.