Glossary of Definitions & Terminology

Question 1

AAA

Answer 1

Authentication, Authorization, and Accounting. Authentication confirms the identity of a user or device. Authorization determines what the user or device is allowed to do. Accounting records information about access attempts, including inappropriate requests

Question 2

Access Interface

Answer 2

A LAN network design term that refers to a switch interface connected to end-user devices.

Question 3

Access Link

Answer 3

In Frame Relay, the physical serial link that connects a Frame Relay DTE device, usually a router, to a Frame Relay switch. The access link uses the same physical layer standards as do point-to-point leased lines.

Question 4

Access Point

Answer 4

A wireless LAN device that provides a means for wireless clients to send data to each other and to the rest of a wired network, with the AP connecting both wireless LAN and wired Ethernet LAN.

Question 5

Accounting

Answer 5

In security, the recording of access attempts. See AAA.

Question 6

Ad Hoc Mode

Answer 6

In wireless LANs, a method or mode of operation in which clients send data directly to each other without the use of a wireless access point (AP).

Question 7

Adjacent-Layer Ineraction

Answer 7

The general topic of how on one computer, two adjacent layers in a networking architectural model work together, with the lower layer providing services to the higher layer.

Question 8

Administrative Distance (AD)

Answer 8

In Cisco routers, a means for one router to choose between multiple routes to reach the same subnet when those routes were learned by different routing protocols. The lower the administrative distance, the better the source of the routing information.

Question 9

ADSL

Answer 9

Asymmetric digital subscriber line. One of many DSL technologies, ADSL is designed to deliver more bandwidth downstream, from the central office (CO), than upstream.

Question 10

Anti-X

Answer 10

The term used by Cisco to refer to a variety of security tools that help prevent various attacks, including antivirus, anti-phishing, and anti-spam.

Question 11

ARP

Answer 11

Address Resolution Protocol. An Internet protocol used to map an IP address to a MAC address. Defined in RFC 826.

Question 12

Asymmetric

Answer 12

A feature of many Internet access technologies, including DLS, cable, and modems, in which the downstream transmission rate is higher than the upstream transmission rate.

Question 13

Asynchronous

Answer 13

The lack of an imposed ordering on a bit stream. Practically, both sodes agree to the same speed, but there is no check or adjustment of the rates if they are slightly different. However, because only 1 byte per transfer is sent, slight differences in clock speed are not an issue.

Question 14

ATM

Answer 14

Asynchronous Transfer Mode. The international standard for cell relay in which multiple service types (such as voice, video, and data) are conveyed in fixed length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware thereby reducing transit delays.

Question 15

Authentication

Answer 15

In security, the verification of the identity of a person or process. See AAA.

Question 16

Authorization

Answer 16

In security, the determination of the rights allowed for a particular user or device. See AAA.

Question 17

Autonomous System

Answer 17

An internetwork in the administrative control of one organization, company, or governmental agency, inside which that organization typically runs an Interior Gateway Protocol (IGP)

Question 18

Auxiliary Port

Answer 18

A physical connector on a router that is designed to be used to allow a remote terminal, or PC with a terminal emulator, to access a router using an analog modem.

Question 19

Back-to-Back Link

Answer 19

A serial link between two routers, created without CSU/DSUs, by connecting a DTE cable to one router and DCE cable to the other. Typically used in labs to build serial links without the expense of an actual leased line from a Telco.

Question 20

Balanced Hybrid

Answer 20

A term that refers to a general type of routing protocol algorithm, the other two being distance vector and link state. The Enhanced Interior Gateway Routing Protocol (EIGRP) is the only routing protocol that Cisco classifies as using a balanced hybrid algorithm.

Question 21

ACL

Answer 21

Access Control List. An ACL is a sequential collection of permit and deny conditions that are applied to traffic passing through a switch or router.

Question 22

TE1 - Technical Definition

Answer 22

ISDN-compatible equipment. In other words, terminal equipment that can interface directly to an ISDN circuit via a four-wire twisted-pair S or T interface. Switches and routers must be natively ISDN-compatible in order to connect to ISDN circuits, typically at the U reference point on the local loop.Telephone sets and data terminals need not be ISDN-compatible.Those not compatible are classified as TE2 and connect through a terminal adapter (TA).

Question 23

TE2 - Technical Definition

Answer 23

Terminal equipment that is not ISDN-compatible. TE2 equipment must connect through a terminal adapter (TA), also known as an ISDN modem, that resolves issues of incompatibility.Telephone sets and data terminals generally are classified as TE2, as the cost of ISDN compatibility generally is considered prohibitive.

Question 24

TA - Ttechnical Definition

Answer 24

Synonymous with ISDN modem. An interface adapter for connecting one or more non-ISDN devices (e.g., telephone sets or PCs) to an ISDN network. A TA is ISDN data communications equipment (DCE) that performs protocol conversion for equipment that is not ISDN-compatible.

Question 25

DCE - Technical Definition

Answer 25

Also known as data circuit terminating equipment (DCTE). Equipment that interfaces data terminal equipment (DTE) to a wide area network (WAN), resolving any issues of incompatibility. Incompatibility issues can include signal format (digital versus analog), voltage level, signaling speed, and bit density. DCE includes modems, digital service units (DSUs), channel service units (CSUs), and front-end processors (FEPs).

Question 26

DSU/CSU - Technical Definition

Answer 26

(Digital (or Data) Service Unit/Channel Service Unit) A pair of communications devices that connect an in-house line to an external digital circuit (T1, DDS, etc.). It is similar to a modem, but connects a digital circuit rather than an analog one.

The CSU terminates the external line at the customer’s premises. It also provides diagnostics and allows for remote testing. If the customer’s communications devices are T1 ready and have the proper interface, then the CSU is not required, only the DSU.

The DSU does the actual transmission and receiving of the signal and provides buffering and flow control. The DSU and CSU are often in the same unit. The DSU may also be built into the multiplexor, commonly used to combine digital signals for high-speed lines.

Question 27

ISDN - Technical Definition

Answer 27

A set of ITU-T Recommendations describing a set of interfaces for access to a digital public switched telephone network (PSTN) intended to provide ubiquitous access to a wide range of services, including voice, data, video, and multimedia.The I series ISDN Recommendations map into the OSI Reference Model at the bottom three layers:

Question 28

Four-wire Circuit - Technical Definition

Answer 28

A circuit that supports transmission in both directions over separate physical links or paths in support of full duplex (FDX), i.e., simultaneous two-way, transmission.The distinguishing characteristic of a four-wire circuit, as opposed to a two-wire circuit, is its ability to support multi-channel communications and out-of-band signaling and control. A physical four-wire circuit, the traditional means of provisioning, is a circuit comprising four physical twisted-pair copper wires in a two-pair configuration, with one pair supporting transmission in the forward direction and the other pair supporting transmission in the reverse direction. A logical four-wire circuit comprises two-wires in a single-pair configuration. A four-wire circuit also can be provisioned as a radio circuit, which is wireless, of course. Four-wire circuits are used in bandwidth-intensive local loops, particularly multi-channel loops, and backbone circuits. Specific examples include DDS, ISDN,T/E-carrier, and SDH/SONET.

Question 29

DaaS

Answer 29

Desktop as a service (DaaS) is the outsourcing of a virtual desktop infrastructure (VDI) to a third party service provider.

Question 30

Programmable Networking

Answer 30

A programmable network is one in which the behavior of network devices and flow control is handled by software that operates independently from network hardware.

The term programmable networking is used by some vendors as a synonym for software-defined networking (SDN). In its infancy, SDN was often referred to as the “Cisco killer” because it supports a switching fabric across multi-vendor commodity hardware.

In response, Cisco has been promoting the term programmable networking to describe a future that goes beyond simply decoupling control from hardware to actually permitting a network engineer to re-program the entire network infrastructure instead of having to re-build it manually. Cisco calls its vision for a programmable network “Open Network Environment” (Cisco ONE).