Chapter 4 - Ethernet Technology

Question 1

Authentication server

Answer 1

In a network using 802.1X user authentication, an authentication server (typically, a RADIUS server) checks a supplicant’s credentials. If the credentials are acceptable, the authentication server notifies the authenticator that the supplicant is allowed to communicate on a network. The authentication server also gives the authenticator a key that can be used to securely transmit data during the authenticator’s session with the supplicant.

Question 2

Authenticator

Answer 2

In a network using 802.1X user authentication, an authenticator forwards a supplicant’s authentication request on to an authentication server. After the authentication server authenticates the supplicant, the authenticator receives a key that is used to communicate securely during a session with the supplicant.

Question 3

Carrier sense multiple access collision detect (CSMA/CD)

Answer 3

Used on an Ethernet network to help prevent a collision from occurring and to recover if a collision does occur. CSMA/CD is only needed on half-duplex connections.

Question 4

Collision

Answer 4

A collision occurs when two devices on an Ethernet network simultaneously transmit a frame. Because an Ethernet segment cannot handle more than one frame at a time, both frames become corrupted.

Question 5

Designated port

Answer 5

In a STP topology, every network segment has a single designated port, which is the port on that segment that is closest to the root bridge, in terms of cost. Therefore, all ports on a root bridge are designated ports.

Question 6

Ethernet

Answer 6

Ethernet is a Layer 1 technology developed by Xerox and encompasses a variety of standards, which specify various media types, speeds, and distance limitations.

Question 7

Full-duplex

Answer 7

This connection allows a device to simultaneously transmit and receive data.

Question 8

Half-duplex

Answer 8

A half-duplex connection allows a device to either receive or transmit data at any one time. However, a half-duplex device cannot simultaneously transmit and receive.

Question 9

Link aggregation

Answer 9

As defined by the IEEE 802.3ad standard, link aggregation allows multiple physical connections to be logically bundled into a single logical connection.

Question 10

Nondesignated port

Answer 10

In STP terms, nondesignated ports block traffic to create a loop-free topology.

Question 11

Power over Ethernet (PoE)

Answer 11

Defined by the IEEE 802.3af and 802.3at standards, PoE allows an Ethernet switch to provide power to an attached device (for example, a wireless access point, security camera, or IP phone) by applying power to the same wires in a UTP cable that are used to transmit and receive data.

Question 12

Root port

Answer 12

In a STP topology, every nonroot bridge has a single root port, which is the port on that switch that is closest to the root bridge, in terms of cost.

Question 13

Spanning Tree Protocol (STP)

Answer 13

Defined by the IEEE 802.1D standard, it allows a network to have redundant Layer 2 connections, while logical preventing a loop, which could lead to symptoms such as broadcast storms and MAC address table corruption.

Question 14

Supplicant

Answer 14

In a network using 802.1X user authentication, a supplicant is the device that wants to gain access to a network.

Question 15

Trunk

Answer 15

In the context of an Ethernet network, this is a single physical or logical connection that simultaneously carries traffic for multiple VLANs. However, a trunk also refers to an interconnection between telephone switches, in the context of telephony.

Question 16

Virtual LAN (VLAN)

Answer 16

A single broadcast domain, representing a single subnet. Typically, a group of ports on a switch is assigned to a single VLAN. For traffic to travel between two VLANs, that traffic needs to be routed.