U–Z
unicast.

A packet that is addressed to only one device.

Variable-Length Subnet Masking.
See [VLSM. Variable-Length Subnet Masking. When several subnets of a major net are subnetted with differing lengths; for example, 10.1.1.0/24 and 10.1.2.0/25 are VLSM subnets. 10.1.1.0/24 and 11.1.2.0/25 are not because they are not in the same major network.]
virtual LAN.
See [VLAN. virtual LAN. A term used for networks attached to switched links, which are divided into separate broadcast domains or subnets using ISL.]
virtual link.

A link between some other area and area 0 (the core) in an OSPF network; the link effectively extends area 0 so that it reaches isolated areas of the network.

VLAN. virtual LAN.

A term used for networks attached to switched ...

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