TCP/IP Guide

DNS Name Resolution Efficiency Improvements: Caching and Local Resolution

The basic resolution techniques—iterative and recursive—can be considered complete from an algorithmic standpoint. By starting at the top (root) and working our way down, we are "guaranteed" to always eventually arrive at the server that has the information we need. I put guaranteed in quotation marks because, as always, there are no real guarantees in networking—we might have asked for a nonexistent name, or a server might have bad data, for example. But in the absence of such atypical problems, the process leads to the information eventually.

The problem is that last word: eventually. Both iterative and recursive resolution will get us to the right server, but they take ...