Latency requirements determines the degree of user satisfaction about the web service. Software development practices shall consider the end-to-end latency as one of user-oriented characteristics during the entire life-cycle of an application. Latency budget defines latency target and non-functional requirements for distributed systems.
We have learned that resolution of human-friendly names into network addresses is a pre-requirement of any Internet service transaction. Therefore, latency of the DNS infrastructure contributes to the overall user-experience. A slow DNS gives the impression that the service is slow.