Fall 2009 Study Guide Problems

bunchlearnedNetworking and Communications

Oct 30, 2013 (3 years and 9 months ago)

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Fall

2009

Study Guide Problems

Chapters 14, 15, 16, 17


There will be 3 questions about subnetting in the final exam.


Chapter 14

1.

What is DNS server? How many DNS servers can be set in a network?

DNS server is a computer that is running DNS server software

that provides domain name resolution
services to other computers in the network.

As many DNS servers as necessary


2.

What is domain name resolution?

The process of finding the corresponding IP address of a domain name


3.

What is hierarchical name space? What
is flat name space? Which name space is used in domain
name?

Hierarchical name space: a naming system that requires
the name to consist of several parts (several
levels)

Flat name space: a naming system that does not require the name to consist of several
parts

Domain name uses the hierarchical name space


4.

Assume that a.b.c.d is a FQDN. What is the host name? What is the top level domain? What is
the second level domain?

Host name: a

Top level domain: d

Second level domain: c


5.

Give 5 examples of the Intern
et’s top level domain. Give 5 examples of the Internet’s second level
domain for .com top level domain.

Internet’s top level domains: .com, .net , .gov, .edu, .tv

Internet’s second level domain from .com: cnn, amazon, yahoo, google, ebay


6.

The local DNS ser
ver has the addresses of … servers

ROOT


7.

The ROOT DNS server has the addresses of … servers

Top level


8.

The top level DNS server has the addresses of … servers

Second level


9.

The second level DNS server has the addresses of … servers

Third level and some hos
ts


10.

In the Internet, which DNS server has the addresses of the .com DNS server?

ROOT


11.

In the Internet, which DNS server has the addresses of the yahoo.com DNS server?

.com


12.

In the Internet, which DNS server has the addresses of the www.yahoo.com DNS server
?

Yahoo.com


13.

What does DNS resolver cache store?

Electronic database that stores all of the domain names and their corresponding IP addresses that
have been

successfully resolved


14.

Select all that apply. Which of the followings is a valid name based upon th
e hierarchical name
space?

a.

a.b.c.d.e

(
valid
)

b.

abcde

c.

uah.edu

(
valid
)

d.

c1.uah.edu

(
valid
)

e.

John_Adams

f.

Sam1972

g.

1

h.

A


15.

Select all that apply. Which of the followings is a valid name based upon the flat name space?

a.

a.b.c.d.e

b.

abcde

(
valid
)

c.

uah.edu

d.

c1.uah.edu

e.

John_Ad
ams

(
valid
)

f.

Sam1972

(
valid
)

g.

1

(
valid
)

h.

A

(
valid
)


16.

Select all that apply. “Root DNS servers” have the addresses of ………

a.

Top level domain servers

b.

.com servers

c.

.net servers

d.

.edu servers

e.

.gov servers

f.

yahoo.com servers

g.

aol.com servers

h.

uah.edu servers

i.

harvard.edu

servers


17.

Select all that apply. “.com DNS servers” have the addresses of ………

a.

Top level domain servers

b.

.com servers

c.

.net servers

d.

.edu servers

e.

.gov servers

f.

yahoo.com servers

g.

aol.com servers

h.

uah.edu servers

i.

harvard.edu servers


18.

Select all that apply. “.edu
DNS servers” have the addresses of ……….

a.

Top level domain servers

b.

.com servers

c.

.net servers

d.

.edu servers

e.

.gov servers

f.

yahoo.com servers

g.

aol.com servers

h.

uah.edu servers

i.

harvard.edu servers


19.

Select all that apply. “yahoo.com DNS servers” have the addresses o
f ……..

a.

www.yahoo.com computers

b.

.com servers

c.

.edu servers

d.

.net servers


20.

Select all that apply. “uah.edu DNS servers” have the addresses of ……..

a.

cas.uah.edu computers

b.

www.uah.edu computers

c.

eng.uah.edu computers

d.

.com servers

e.

.edu servers

f.

.net servers


21.

Selec
t all that apply. Root DNS Server contains addresses of ………

a.

Top level domain DNS server

b.

Second level domain DNS server

c.

Third level domain DNS server


22.

Select all that apply. Top level domain DNS server contains addresses of ………

a.

Root DNS server

b.

Second level
domain DNS server

c.

Third level domain DNS server


Chapter 15

1.

True or False. The dynamic routing capability enables a router to determine the best route to
deliver the packet to the actual destination.

True
.

The static cannot do it because it has predetermin
ed routes to go from
each point (node) to each of
the other points (nodes)


2.

Routing table contains information used by the router to …… packet to the actual destination

Route


3.

What is routing metrics? What is routing algorithm? What are examples of routing

metrics?

Routing metrics: A value used by a routing algorithm to determine whether one route should perform
better than another. Examples: bandwidth, time delay, traffic load, hop count

Routing algorithm: The formula to determine the most efficient route


4.

What is static routing? What is dynamic routing?

Static routing: The method of routing a packet based on routing information that is entered manually
(by network administrator) into the routing table

Dynamic routing: The method of routing a packet based o
n routing information that is created
automatically by a network layer protocol. This method allows the packet to be delivered by using the
best route available, and to be automatically rerouted if there is a problem with the default route.


5.

What are the d
ifferences between Static and Dynamic routing?

See the table on slide 6 in Chapter 15 slide set
. You have to remember all of them.


6.

What are examples of dynamic routing?

RIP, OSPF, BGP, IS
-
IS, EIGRP


7.

What are examples of Distance Vector dynamic routing pro
tocols? Link State? IRP? ERP?

Distance Vector: RIP, BGP

Link State: OSPF, IS
-
IS

IRP: RIP

ERP: BGP


8.

What is autonomous system (AS)?

A group of routers controlled by a single authority



9.

......... is used by routers within an autonomous system (AS)

IRP such
as RIP


10.

......... is used by edge routers

ERP such as BGP


11.

……… improves the reliability of a network (select one)

a.

Dynamic routing

b.

Static routing

Dynamic routing


12.

In the Internet, one network is connected to another network by using ………

Router


13.

What is ISP
? What is the difference between Local and Backbone ISP?

An organization that owns the public network in the Internet, hence, allows public users to connect
their computer to the Internet (provides Internet connection services to public)

Local ISP owns a s
mall network (one city, several cities, one state, several states, never a nation)

Backbone ISP owns a large network (one nation, several nations)


14.

What are examples of backbone ISPs? What is an example of a local ISP?

Backbone ISPs: AT&T, UUNET (MCI), Spr
ing, Qwest, Level 3 Communications

Local ISPs: Knology


15.

… is used by the router to route the packet from one network to another

a.

IP address (logical address)

b.

MAC address (physical address)

IP address (logical address)


16.

A private network can be connected to
the Internet by using …… (select all that apply)

a.

A set of valid Internet IP Addresses

b.

NAT

c.

Proxy Server

Answers a., b., and c.


17.

What is the difference between NAT and Proxy Server? What are the advantages of using NAT?
What is the disadvantage of using NAT
? What are the advantages of using Proxy Server? What is
the disadvantage of using Proxy Server?

NAT only
replace

the

private IP address into
the

valid Internet IP address

in the original packet from
the local computer

P
roxy server recreates an entirely ne
w packet containing the same information as the one from the
original

packet. This new packet has the valid Internet IP address

Advantages of NAT: a cheaper solution to connect a network to the Internet, a more secured solution
to connect a network to the
Internet

Disadvantage of NAT: a Web server cannot be installed behind the NAT. It has to have its own valid
Internet IP address.

Advantages of proxy server: a cheaper solution to connect a network to the Internet, a more secured
solution to connect a netwo
rk to the Internet, can speed up Internet transactions, can filter Internet
transactions

Disadvantage of proxy server: a Web server cannot be installed behind the NAT. It has to have its
own valid Internet IP address.


18.

To connect a network to the Internet
by using a single public IP address, …… must be used
(select all that apply)

a.

NAT

b.

Proxy Server

c.

Switch

d.

Hub

NAT

Proxy Server


Chapter 16

1.

What is remote connectivity technology?

The technology to allow us to connect a computer (network) to another computer (ne
twork) at a
remote location


2.

What are examples of remote connectivity technology?

PSTN (POTS), ISDN, DSL, Cable Modem
, T1, T3, Sonet/SDH and

OC


3.

Which remote connectivity technology uses analog technology? Which remote connectivity
technology uses digital
technology?

Analog: PSTN (POTS)

Digital: ISDN, DSL, Cable Modems, T1, T3, Sonet, OC


4.

Which remote connectivity technology uses telephone network? Which remote connectivity
technology uses television cable network?

Telephone network: PSTN (POTS), ISDN, DSL

TV cable network: Cable Modem


5.

Which remote connectivity technology uses fiber optic exclusively?

Sonet/SDH and OC


6.

Which remote connectivity technology uses dial up connection? Which remote connectivity
technology uses dedicated connection?

Dial up: PSTN
(POTS), ISDN

Dedication connection: DSL, Cable Modem, T1, T3, Sonet/SDH and OC


7.

What are the differences between analog and digital technology?

Analog: older technology, using sine wave signal as the data carrier, not reliable, slower

Digital: newer techno
logy, using electronic pulse as the data carrier, reliable, faster


8.

What is modem? What is modulation? What is demodulation?

Modem: A device to convert digital signal into analog signal and vice versa

Modulation: The process of converting digital signal in
to analog signal

Demodulation: The process of converting analog signal into digital signal


9.

What are the differences between SLIP and PPP?

See the list of these differences on slide 8 of Chapter 16 slide set.


10.

Which remote connectivity technology uses SLIP
? Which remote connectivity technology uses
PPP?

SLIP: PSTN (POTS)

PPP: PSTN (POTS), ISDN


11.

What are examples of dial up protocols?

SLIP, PPP


12.

What are the advantages and the disadvantages of dial up connection over PSTN?

Adv: The cheapest, the most widely
available

Disadv: The slowest the least reliable


13.

What are two types of ISDN services?

BRI (up to 2 X 64 Kbps), PRI (up to 23 X 64 Kbps)


14.

What is B channel in ISDN? What is D channel is ISDN?

B channel carries the actual user data

D channel carries the co
ntrol data


15.

What is the difference between BRI and PRI?

BRI provides 2 64 Kbps B channels + 1 16 Kbps D channel

PRI

provides 23 64 Kbps B channels + 1 64 Kbps D channel


16.

Which remote connection technology uses DSLAM?

DSL


17.

What is symmetric DSL? What is asy
mmetric DSL?

Symmetric: Download throughput is the same as upload throughput

Asymmetric: Download throughput is faster than upload throughput


18.

What is an example of application that is appropriate for asymmetric DSL? What is an example of
application that

requires symmetric DSL?

Asymmetric: client application

Symmetric: server application


19.

What is the major weakness of DSL?

The farther the node from DSLAM, the slower the actual throughput


20.

C
able modem based on

a.

symmetric
technology

b.

asymmetric technology

As
ymmetric


21.

What is the weakness of cable modem?

The more subscribers online, the slower the actual throughput

Security (a number of subscribers are connected to one another in a local network, hence, allows the
use of packet sniffer to capture packets that
are sent to any one of these subscribers)


22.

Which remote connectivity technology is a
leased

line?

T1, T3, Sonet/SDH and OC


23.

Which remote connectivity technology uses CSU/DSU?

T1, T3


24.

What are the advantages and disadvantages of T1 and T3?

Adv: The actual t
hroughput is more consistent guaranteed speed (because the line is not shared by
other subscribers), fast

Disadv: Expensive, could be inefficient if the subscriber does not use the line around the clock


25.

Different versions of SONET/SDH are named by using
…… level

OC


26.

How many fiber optic ring cables are
usually
available in a single SONET/SDH network?

Two (uses double ring physical topology that allows “self healing mechanism”.


Chapter 17

1.

What are examples of internal threats? What are examples of externa
l threats?

Internal threats: unauthorized access, data destruction, system crash/failure, virus

External threats: telephone/email scams, dumpster diving, physical theft


2.

Security is …… related to functionality. What is the meaning of this statement?

Negati
vely related. It means that increasing security level of your computer (network) will always
decrease the functionality level of your computer (network)


3.

What are methods to avoid internal and external threats?

Policy (e.g., user account), physical protec
tion, educating/informing users about potential network
threats, using network security technology


4.

What is policy? What are examples of policy?

Policy is a procedure that defines what must be done to perform certain task

Example: User account (i.e., usern
ame and password that must be used to access network
resources)


5.

What is the difference between private key and public key encryption?

How many keys are
used to encrypt and decrypt data in private key encryption? How many keys are used to
encrypt and decry
pt data in public key encryption?

Which key is used to encrypt? Which
key is used to decrypt?


6.

What are examples of firewall?

NAT, Proxy server, Network layer firewall/packet filter


7.

What is digital certificate? What/who provides digital certificates?

Digi
tal certificate: a file, approved by certificate authority (CA), that guarantees that the Web site’s
digital signature is true (i.e., guarantees that the Web site is truly what it is claiming to be)


8.

What is SSL? How can we identify if a site
that
uses SSL
?

Secure socket layer: Cryptographic protocols that provide secure communications on the Internet for
such things as Web browsing and e
-
mail.

All sites that use SSL always has addresses that start with HTTPS, instead of HTTP