802.3af Power over Ethernet (POE)
PoE powered devices can draw up to about 13 W over the link. Power is supplied as 350mA@48V and limited to 15.4 W, but the voltage drop over the maximum 100 feet of cable results in usable power of around 13 W
802.3at (PoE+) POE improved Injector
PoE powered devices can draw up to about 25 W. PoE+ allows for a broader range of devices to be powered such as cameras with pan/tilt/zoom capabilities, door controllers, and thin client computers.
ACL (Access Control List)
The permissions attached to or configured on a network resource, such as folder, file, or firewall.
The ACL specifies which subjects (user accounts, host IP addresses, and so on) are allowed or denied access and the privileges given over the object (read only, read/write, and so on).
ad-hoc mode
A temporary network mode in which devices connect to each other directly without an intermediary networking device.
ad-hoc network
A peer-to-peer network created for the current print session.
ADSL
(Asymmetrical Digital Subscriber Line) A consumer version of DSL that provides a fast downlink but a slow uplink. The upstream rate is between 64 Kbps and 1 Mbps and the downstream rate it 500 Kbps to 8 Mbps.
AES
(Advanced Encryption Standard) Modern encryption suite providing symmetric encryption (the same key is used to encrypt and decrypt). AES is a very strong cipher with many applications, including being part of the WPA2 Wi-Fi encryption scheme.
agent
A process running on an SNMP compatible network device that sends information to an SNMP (Simple Network Management Protocol) manager.
AHCI
(Advanced Host Controller Interface) A logical interface used by SATA drives to communicate with the bus.
ALU
(Arithmetic Logic Unit) A circuit in the CPU that performs integer-based calculations and performs bit-wise logical calculations.
AMD64
AMD's 64-bit instruction set that was also adopted by Intel for its 64-bit desktop and mobile line. Intel refers to it as EM64T or Intel 64.
Android application package
(APK) Third-party or custom programs that are installed directly through an APK file, giving users and business the flexibility to install apps directly on Android devices.
AP (Access Point)
A device that provides connectivity between wireless devices and a cabled network. APs with Internet connectivity located in public buildings (cafes, libraries, and airports, for instance) are often referred to as hotspots.
APIPA (Automatic Private IP Addressing)
A means for Windows clients configured to obtain an address automatically that could not contact a DHCP server to communicate on the local subnet. The host randomly selects an address from the range 169.254.x.y. This is also called a link-local address.
Application protocols layer
In the TCP/IP suite, numerous protocols used for network configuration, management, and services reside at this level. Application protocols use a TCP or UDP port to connect the client and server.
ARP (Address Resolution Protocol)
When two systems communicate using IP, an IP address is used to identify the destination machine. The IP address must be mapped to a device (the network adapter's MAC address). ARP performs the task of resolving an IP address to a hardware address. Each host caches known mappings in an ARP table for a few minutes. It is also a utility used to manage the ARP cache.
authentication
A means for a user to prove their identity to a computer system. Authentication is implemented as either something you know (a username and password), something you have (a smart card or key fob), or something you are (biometric information). Often, more than one method is employed (2-factor authentication).