DHCP supports three methods for IP address allocation - Anvari.Net

aliveboonevilleNetworking and Communications

Oct 28, 2013 (3 years and 7 months ago)


Prof. M. Anvari Page


460 Final Exam

Strayer University

(Arlington Campus)

CIS 460 Final Exam

Student Name:

June 11, 2003

1. What are the advantages of Using Dynamic Addressing for End Systems?

• Reduces the configura
tion tasks required to connect end systems

• Supports users who change offices frequently

• Built into desktop protocols such as AppleTalk and Novell NetWare

• Minimizes configuration tasks

2. What are the
three methods of the IP address allocation us
ed by
the Dynamic Host
Configuration Protocol (DHCP)

DHCP supports three methods for IP address allocation

Automatic allocation

assigns permanent IP address to a client

Dynamic allocation

assigns an IP address to a client for a limited period
of time


network administrator assigns permanently and DHCP merely conveys
address information

3. What is the Private Addresses in an IP Environment? And what are the Caveats with
Private Addressing?

•These are addresses assigned by inter
nal networks and hosts without any coordination
from an ISP or the Internet Assigned Numbers Authority

•An advantage is security. Private numbers are not advertised on the Internet

•Helps meet goals for adaptability and flexibility

•Network can advertise
just one network number or small block of numbers to the

•Can reserve scarce Internet addresses for public servers

Caveats with Private Addressing

•Outsourcing network management is difficult

•Difficulty of communicating with partners, vendors, s
uppliers, and other outsiders

•Easy to forget to use a structured model

•Assign in a structured, hierarchical fashion

Prof. M. Anvari Page


460 Final Exam

4. Explain the differences of Classless Routing Versus Classful Routing.

•IP address contains a prefix part and a host part

Prefix i
dentifies a block of host numbers and is used for routing that block

Traditional (classful routing) does not transmit any information about the prefix length

Traditional IP hosts and routers had a limited capability to understand prefix lengths
and subne

• Classless routing protocols transmit a prefix length with an IP address

• Classless routing protocols include Routing Information Protocol (RIP) V2, Enhanced
Interior Gateway Routing Protocol (Enhanced IGRP), Open Shortest Path First (OSPF),
Border Ga
teway Routing Protocol (BGP) & Intermediate System
to Intermediate System

5. What are the functions of Transparent Bridge and how does it work?

• Most common Ethernet environments

• A transparent bridge (switch) connects one or more LAN segm
ents so that end
systems on different segments can communicate with each other transparently

• Looks at the source address in each frame to learn location of network devices

• It develops a switching table

• Receives a packet look sup address in switch ta

• If no address it sends the frame out every port like a broadcast frame

• Send Bridge Protocol Data Unit (BPDU) frames to each other to build and maintain the
spanning tree

• Sends BPDU to a multicast address every two seconds

6. What are the benef
its of Source
Route Switching?

•Uses explorer frames

routes explorer

take all possible paths, take just one route back

route explorer

takes just one path and response take all paths or just one back

With single
route explorer frames th
e spanning
tree algorithm

can be used to
determine a single path

Scalability is impacted by amount of traffic when all
routes explorer frames are used


Rings can be segmented without adding new ring numbers

can be incrementally upgraded to tra
nsparent bridging with minimal disruption or

does not need to learn the MAC addresses of devices on the other side of source

can support parallel source routing paths

can support duplicate MAC addresses

Prof. M. Anvari Page


460 Final Exam

7. What are the Rou
ting Protocol Metrics?

• Used to determine which path is preferable when more than one path is available

• Vary on which metrics are supported

• Distance
vector use hop count

• Newer protocols take into account delay, bandwidth, reliability and other fac

• Metrics can effect scalability

8. Briefly describe the Routing Protocols Convergence.

• Convergence is the time it takes for routers to arrive at a consistent understanding of
the Internet work topology after a change takes place

• Understand

the frequency of changes, links that fail often, etc

• Convergence time is a critical design constraint

Convergence starts when a router notices a link has failed

If a serial link fails it can start immediately. If it uses keepalive frames it starts
nvergence after it has been unable to send two or three keepalive frames

If use hello packets and the hello timer is shorter than the keep alive timer then routing
protocol it can start convergence sooner

9. Why some network use Redistribution betwee
n Routing Protocols

Redistribution allows a router to run more than one routing protocol and share routes
among routing protocols

Network administrator must configure redistribution by specifying which protocols
should insert routing information into
other protocol’s routing tables

A router can learn about a destination from more than one protocol

10. Describe the Mobile Hosts Network concept.

• Classless routing and discontiguous subnets support mobile hosts

• A mobile host is a host that moves
from one network to another and has a statically
defined IP address

• Routers use the longest prefix available that is appropriate for the destination address
in the packet