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IANA port 42
42
TCP/UDP port 42 · Host Name Server (name / nameserver)
The internet’s list of door numbers gives 42 to Host Name Server. Name lived there before DNS took port 53. One well-known port among 1024.
What it supports
IANA assigns TCP and UDP 42 to service names name and nameserver, description Host Name Server. That was the ARPA Host Name Server Protocol (IEN 116, Postel, August 1979). RFC 1700 still prints nameserver 42/tcp and 42/udp. DNS later took port 53. Microsoft later used 42 for WINS replication. Historical encoding of name, not a second ASCII asterisk.
What it does not
Not DNS port 53. Not a recovered “why 42” from Postel. 41 and 43 are also assigned. Huge opportunity space (0–65535). WINS reuse is the same number, not a second object. DNS RR type 42 (APL) is a series member, not this card. IEN 116 is the protocol text, not the port table.
ExactnessDesignation
Form42
Unitport
Strengthattested