101 NIC Host Name Server - System Port

101 is a System Port. Transport Protocol TCP UDP , 101 Service Name hostname, Service Name Description: NIC Host Name Server.

Port	Protocol	Service Name	Description	Source
101	TCP UDP	hostname	NIC Host Name Server	IANA
101	TCP		NIC host name,Official	wikipedia
101			Skun	simovits.com
101	TCP UDP		Udps	bekkoame
101	TCP UDP	hostname	NIC Host Name Server	bekkoame

Port	Service Name	Description
932		Unassigned
1330	streetperfect	StreetPerfect
1476	clvm-cfg	clvm-cfg
1838	talnet	TALNET
3075	orbix-locator	Orbix 2000 Locator
3313	uorb	Unify Object Broker
3467	rcst	RCST
4048		Unassigned
4288	vrml-multi-use	VRML Multi User Systems
4504		Unassigned

A port is an endpoint of communication in an operating system. While the term is also used for hardware devices, in software it is a logical construct that identifies a specific process or a type of service.

Port numbers are assigned in various ways, based on three ranges: System Ports (0-1023), User Ports (1024-49151), and the Dynamic and/or Private Ports (49152-65535);

The Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root) processes or by programs executed by privileged users. Ports are used in the TCP [RFC793] to name the ends of logical connections which carry long term conversations. For the purpose of providing services to unknown callers, a service contact port is defined. This list specifies the port used by the server process as its contact port. The contact port is sometimes called the "well-known port". To the extent possible, these same port assignments are used with the UDP [RFC768]. The range for well-known ports managed by the IANA is 0-1023.
DYNAMIC AND/OR PRIVATE PORTS Registered Ports are those from 1024 through 49151.
The Dynamic and/or Private Ports are those from 49152 through 65535