U

UDP

See User Datagram Protocol (UDP).

Uniform Resource Locator (URL)

A way of identifying a document on the Internet. It consists of the protocol used to access the document and the domain name or IP address of the host that holds the document; for example, http://www.sybex.com.

uninterruptible power supply (UPS)

A device that can provide short-term power, usually by using batteries.

Unshielded Twisted Pair (UTP)

The most common networking cable currently in use; Unshielded Twisted Pair (UTP) is 8-wire cabling used with Ethernet.

uptime

The amount of time a particular computer or network component has been functional.

URL

See Uniform Resource Locator (URL).

usage policies

Defined policies governing computer usage.

user

The person who is using a computer or network or a resource.

User Datagram Protocol (UDP)

The protocol at the Host-to-Host layer of the TCP/IP Department of Defense (DoD) model, which corresponds to the Transport layer of the OSI model. Packets are divided into datagrams, given numbers, sent, and put back together at the receiving end. UDP is a connectionless protocol. See also connectionless, Open Systems Interconnection (OSI) model.

user-level security

A type of network security in which user accounts can read, write, change, and take ownership of files. Rights are assigned to user accounts, and each user knows only their own username and password—which makes this the preferred method for securing files.

user management policies

Defined policies that detail user management.