SWRU368C May 2018 – January 2021 CC3100 , CC3100MOD , CC3200 , CC3200MOD
By default, mDNS exclusively resolves host names ending with the .local top-level domain (TLD). The mDNS Ethernet frame is a multicast UDP packet to:
The Ethernet frame content like Questions, Answers, Authority, Additional, and Data fields, including their formats, are identical to those inside a unicast DNS packet. Detailed specification can be found in RFC1034.
Services are found using resource record (RR) queries identical to unicast DNS. RRs store a large variety of records about a domain such as IP addresses (A & AAAA types), pointer record (PTR type), Service locator (SRV type), text (TXT type) and so forth. A full list can be found in the Wikipedia link: List of DNS record types.
A DNS zone database is a collection of resource records. Each resource record specifies information about a particular object. For example, address mapping records a host name to an IP address.
RR queries with types of PTR, SRV, TXT, and A (or AAAA in case of IPv6) are needed for discovering the full-service details.
All answers must be sent in a single response to a query. For example:
An mDNS client must resolve a host name after receiving a PTR record, which includes a service in the interest of the application: