Homework 2 Study Guide

Question 1

Which network layer is responsible for point-to-point network reachability?

Answer 1

The data link layer (L2) is responsible for point-to-point reachability.

Question 2

Which network layer is responsible for end-to-end network reachability?

Answer 2

The network layer (L3) is responsible for end-to-end reachability.

Question 3

What organization is in charge of IP address assignment?

Answer 3

ICANN is the organization responsible for IP address assignment.

Question 4

What information in the IP header is necessary for IP fragmentation?

Answer 4

The following information is found within the IP header and is necessary for IP fragmentation:
Identification
IP Flag (Bits D & M)
Fragment Offset
The checksum isn't part of the header.

Question 5

Routing decisions are based off of what information?

Answer 5

Routing decisions are made at the network layer, therefore they use the IP address of the destination.

Question 6

What network service does the Address Resolution Protocol provide?

Answer 6

The Address Resolution Protocol provides Layer 3 to Layer 2 mapping (pairing IP addresses with MAC addresses.

Question 7

What network layer does DNS belong to?

Answer 7

DNS is a layer 7 protocol, an application layer protocol.

Question 8

What network layer does DHCP belong to?

Answer 8

DHCP is a layer 7 protocol, an application layer protocol.

Question 9

What is the minimum frame body size in 802.11?

Answer 9

In 802.11, the minimum frame body size is 0,

Question 10

What are the operational modes of 802.11-based WLANs?

Answer 10

The operational modes of 802.11 are ad hoc and infrastructure.

Question 11

What wireless access method is better at supporting time-sensitive applications?

Answer 11

PCF (Point coordinated function) is the best method for supporting time-sensitive applications over WLAN, as the AP allows for coordination and a form of QoS.

Question 12

Why is CSMA/CD not used on WLAN? What is used instead?

Answer 12

CSMA/CD isn’t used because wireless antenna cannot send and receive at once, so they cannot detect collisions. CSMA/CA is used instead.

Question 13

Why is the network span of a 100BaseT network is 1/10th of that of a 10BaseT. Why?

Answer 13

A 100BaseT network is much shorter than 10BaseT because both networks have minimum frame sizes, which determine detection time, which determine span.