TestOut Networking Pro Ch 4 Exam Questions and Answers

TestOut Networking Pro Ch 4 Exam Questions and Answers Topology -Answer-Ethernet uses the following networking topologies, depending upon the specification being implemented: • Physical bus, logical bus • Physical star, logical bus • Physical star, logical star Networking Device -Answer-Devices used on Ethernet networks include: • NICs • Hubs (obsolete) • Switches • Routers Transmission Media -Answer-Ethernet supports the following cable types: • Unshielded twisted pair (UTP) cables with RJ45 connectors. This is the most common transmission medium used for Ethernet. • Fiber optic cables, most commonly used in high-speed applications, such as servers or streaming media. • Coaxial cables for older Ethernet implementations (often called thinnet or thicknet networks). Media Access Method -Answer-Ethernet uses a contention-based media access method defined by the IEEE 802.3 standards called Carrier Sense, Multiple Access/Collision Detection (CSMA/CD). Devices use the following process to send data: • Because all devices have equal access (multiple access) to the transmission media, a device listens to the transmission medium to determine if it is free before sending data (carrier sense). • If it is not free, the device waits a random amount of time and listens again to the transmission medium. If it is free, the device transmits its message. • If two devices transmit at the same time, a collision occurs. The sending devices detect the collision (collision detection) and send a jam signal to notify all other hosts that a collision has occurred. • Both devices wait a random length of time before attempting to resend the original message (backoff). Devices with collision detection turned on operate in half-duplex mode; devices with collision detection turned off operate in full-duplex mode Half Duplex -Answer-• Collision detection is turned on. • The device can send or receive in only one direction at a time. • Devices connected to a hub must use half-duplex communication. Up to the rated bandwidth (10 Mbps for 10BaseT, 100 Mbps for 100BaseT, etc.) Full Duplex -Answer-• Collision detection is turned off. • The device can send and receive at the same time. • Requires full-duplex capable NICs. • Requires switches with dedicated switch ports (a single device per port). Double the rated bandwidth (20 Mbps for 10BaseT, 200 Mbps for 100BaseT, etc.) Physical Addresses -Answer-Ethernet devices are identified by using the MAC address, which is burned into the network interface card. Frames -Answer-is a unit of data that is ready to be sent on the network medium. Ethernet frames contain the following components: • The preamble is a set of alternating ones and zeros terminated by two ones (11) that mark it as a frame. • The destination address identifies the receiving host's MAC address. • The source address identifies the sending host's MAC address. • The data is the information that needs to be transmitted from one host to the other. • Optional bits to pad the frame. Ethernet frames are sized between 64 and 1518 bytes. If the frame is smaller than 64 bytes, the sending NIC places "junk" data in the pad to make it the required minimum of 64 bytes. • The cyclic redundancy check (CRC) is the result of a mathematical calculation performed on the frame. The CRC helps verify that the frame contents have arrived uncorrupted. Ethernet Implementations -Answer-10BaseT 10 Mbps (half duplex) 20 Mbps (full duplex) Twisted pair (Cat3, 4, o