DNS update

This document describes an EDNS(0) option that can be used between DNS Update Requesters and authoritative DNS servers to include a lifetime (lease duration) in a DNS Update or DNS Update Response, allowing a server to garbage collect stale Resource Records that have been added by DNS Updates if they are not renewed.

The Service Registration Protocol (SRP) for DNS-based Service Discovery (DNS-SD) uses the standard DNS Update mechanism to enable DNS-SD using only unicast packets. This makes it possible to deploy DNS-SD without multicast, which greatly improves scalability and improves performance on networks where multicast service is not an optimal choice, particularly IEEE 802.11 (Wi-Fi) and IEEE 802.15.4 networks. DNS-SD Service registration uses public keys and SIG(0) to allow services to defend their registrations.

Using this specification of the UPDATE opcode, it is possible to add or delete RRs or RRsets from a specified zone. Prerequisites are specified separately from update operations, and can specify a dependency upon either the previous existence or nonexistence of an RRset, or the existence of a single RR. [STANDARDS-TRACK]