RRsets

An RRset, or resource record set, is a group of DNS resource records that share the same owner name, DNS class, and record type. All members of an RRset have the same TTL (in well-formed zones) and the same data type, while the RDATA may differ between records. For example, an A RRset for the name example.com can contain multiple A records, each providing a different IPv4 address for the same host.

RRsets are the fundamental unit of data in the DNS. When a resolver queries for a name and type, the response may include all records from the corresponding RRset. This means that the presence of multiple records for a name and type is represented as a single logical unit rather than as separate, unrelated entries.

TTL and caching are closely tied to RRsets. Each record carries a TTL, and in practice, records within an RRset typically share the same TTL, which governs how long the records may be cached. Caching and authoritative decision-making operate on the RRset as a whole.

DNSSEC and dynamic updates also rely on RRsets. In DNSSEC, signatures (RRSIG records) cover an entire RRset, ensuring the integrity of all records with the same name, class, and type. In dynamic DNS updates (RFC 2136), changes are applied to RRsets by adding or deleting whole sets, rather than individual records within a set.

Common examples of RRsets include multiple A records for a hostname, multiple NS records for a zone delegation, or multiple MX records for a mail domain.