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U.2 Wikipedia PCPartPicker Forums
Ubuntu A Linux distribution based off of Debian. Wikipedia Website
Ubuntu 16.04 Released April 21, 2016. Ubuntu Insights
ultimate route Routing table entry that has a next-hop IPv4 address or an exit interface. (Dynamic routes or local routes.)
uname Unix command to display the name and version of the computer. Use ver or winveron Windows.
unequal-cost load balancing Distributes traffic over network interfaces even if they are different distances (metrics). Supported by EIGRP.
unfiltered port Nmap port state where an ACK scan returns an RST packet on the scanned port. The unfiltered state means that a port is accessible, but Nmap is unable to determine whether it is open or closed. Nmap
unicast (One to One.) Sending a packet from one host to an individual host. Unicast ranges from 0.0.0.0-255.255.255.255 but some address blocks are reserved for other special uses. Wikipedia
Unicode standard character encoding Wikipedia
Unicornscan Developed to assist security testers in conducting tests on large networks and to consolidate many of the tools needed for large-scale endeavors. Optimizes UDP scanning beyond the capabilities of any other port scanner. Website sectools.org
Unified Modeling Language (UML) Used for modeling object oriented programs.
Uniform Resource Identifier (URI) Can be a URL or a URN. Wikipedia
Uniform Resource Locator (URL) Wikipedia
Uniform Resource Name (URN) Wikipedia
Uniform Service Order Code (USOC)
Unique Identifier (UID) Any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose. Wikipedia
Unique Local Address (ULA) These addresses should not be routable in the global IPv6. Unique local addresses are in the range of FC00::/7 to FDFF::/7. Defined in RFC 4193 October, 2005. Wikipedia RFC 4193
Unity Shell for the GNOME desktop environment from Canonical. First released June 9, 2010. Website Wikipedia
UNIVersal Automatic Computer (UNIVAC) Wikipedia
Universal Character Set (UCS) Wikipedia
Universal Character Set Transformation Format - 32-bit (UTF-32) Wikipedia
Universal Character Set Transformation Format - 8-bit (UTF-8) Wikipedia
Universal Disk Format (UDF) Open file system. Typically used on optical media. Wikipedia
Universal Mobile Telecommunications System (UMTS) Third generation mobile cellular system for networks based on the GSM standard. Wikipedia
Unlock-ADAccount PowerShell cmdlet used to unlock an Active Directory account. TechNet
unordered pair (aka: set) {x, y} Wikipedia
Unified Extensible Firmware Interface (UEFI) Wikipedia
Unified Threat Management (UTM) Wikipedia
Unit Identification Light (UID) Helps physically identify an individual server. HP Community
Universal Plug and Play (UPnP) UDP port 1900 Wikipedia PDF
Universal Serial Bus (USB) Standard connector that replaced the plethora of serial and parallel IO. Designed to be "Plug-and-Play" hot swappable and self-configuring. Supports up to 127 connected devices through a single bus (port) at one time. First introduced January 1996. Wikipedia
Universal Windows Platform (UWP) One app on any screen size. Originally Windows Runtime in Windows 8. Windows Dev Center Microsoft Developer Network
UNIX An operating system developed by Bell Labs with Ken Thompson and Dennis Ritchie. Originally written in the PDP-7 assembly language. OS X and Linux are two popular operating systems based off UNIX. Wikipedia
UNIX Shell Wikipedia
UNIX-to-UNIX Copy Program port 540
unordered list (ul) HTML tag that defines a unordered list marked with bullets. Used with the li tag to create the list. W3Schools
Unshielded Twisted Pair (UTP) Cable found in many Ethernet networks and telephone systems. terminated with an RJ connector, Usually RJ-45 (8P8C) or RJ-11 (6P2C). TIA/EIA-568 is the standard for wire color codes to the pinouts for Ethernet cables.
up/down status up/protocol down. Layer 2 issue: (keepalive, encapsulation, clocking)
Updatable View Can be used to update attributes in the base tables that are used in the view.
uplink port The port used for internet connectivity.
uptime The amount of time a computer has been on since the last reboot. Can be viewed on UNIX-like systems with the uptime command. Use wmic os get lastbootuptime (written as: yyyymmddhhmmss.nnn) for Windows. Wikipedia
USB 1.0 (aka: Low Bandwidth, Low Speed) Up to 1.5Mbps transfer rate. First introduced January 1996. Wikipedia
USB 1.1 (aka: Full Speed) Up to 12Mbps (1.5MBps) transfer rate. Max cable length is 3 meters (18 meters if using the maximum of five hubs). Released in August 1998. Wikipedia
USB 2.0 (aka: High Speed) Up to 480Mbps (60MBps) transfer rate. Max cable length is 5 meters (30 meters if using the maximum of five hubs). Released in April 2000. Wikipedia
USB 3.0 (aka: SuperSpeed) Up to 5Gbps transfer rate. Max cable length is 3 meters (18 meters if using the maximum of five hubs). Released November 12, 2008. Website
USB 3.1 Gen 1 Preserves the existing SuperSpeed transfer rate under a new label USB 3.1 Gen 1, and introduces a new SuperSpeed+ transfer mode, USB 3.1 Gen 2 with the maximum data signaling rate to 10 Gbit/s (1250 MB/s, twice the rate of USB 3.0). Released in July 2013. Website Wikipedia
USB 3.1 Gen 2 Up to 10Gbps transers rate. Website Wikipedia
USB 3.2 Specification for USB. Maximum transfer speed of 2GBps (gigabytes per second). Doubles the speed of existing USB Type-C cables. Published September 22, 2017. USB-IF Tom's Hardware Ars Technica
USB Type-C Reversible 24-pin connector. Standardized August 12, 2014. Wikipedia AnandTech
User Datagram Protocol (UDP) Layer 4 connectionless protocol that has unreliable delivery. (Does not acknowledge if the data is received.) Uses less overhead than TCP. Wikipedia
user interface How a user can interact with a device. This can be Wikipedia
user-group-other (UGO) Acronym for file permissions.
useradd Bash command to add a user account. Linuxers
uTorrent (?Torrent) A P2P application. Wikipedia