Chapter 3 Review Questions

Question 1

What must happen if a DHCP IP conflict occurs?

Answer 1

The administrator must fix the conflict by hand at the DHCP server. If a DHCP conflict is detected, either by the server sending a ping and getting a response or by a host using a gratuitous ARP (arp’ing for its own IP address and seeing if a host responds), then the server will hold that address and not use it again until it is fixed by an administrator

Question 2

Which Application layer protocol sets up a secure session that’s similar to Telnet?

Answer 2

SSH. Secure Shell (SSH) protocol sets up a secure session that’s similar to Telnet over a standard TCP/IP connection and is employed for doing things like logging into systems, running programs on remote systems, and moving files from one system to another.

Question 3

Which of the following mechanisms is used by the client to avoid a duplicate IP address during the DHCP process?

Answer 3

Gratuitous . A host uses something called a gratuitous ARP to help avoid a possible duplicate address. Gratuitous ARP is a sort of “advance notification”, it updates the ARP cache of other systems before they ask for it (no ARP request) or to update outdated information

Question 4

What protocol is used to find the hardware address of a local device?

Answer 4

ARP. Address Resolution Protocol (ARP) is used to find the hardware address from a known IP address

Question 5

Which of the following are layers in the TCP/IP model? (Choose three.)

A. Application

B. Session

C. Transport

D. Internet

E. Data Link

F. Physical

Answer 5

A, C, D. The listed answers are from the OSI model and the question asked about the TCP/IP protocol stack (DoD model). Yes, it is normal for the objectives to have this type of question. However, let’s just look for what is wrong. First, the Session layer is not in the TCP/IP model; neither are the Data Link and Physical layers. This leaves us with the Transport layer (Host-to-Host in the DoD model), Internet layer (Network layer in the OSI), and Application layer (Application/Process in the DoD). Remember, the CCENT objectives can list the layers as OSI layers or DoD layers at any time, regardless of what the question is asking

Question 6

Which class of IP address provides a maximum of only 254 host addresses per network ID?

Answer 6

Class C. A Class C network address has only 8 bits for defining hosts: 28 – 2 = 256

Question 7

What is used as a layer 2 & 3 broadcast for the DHCP Discover message? What Transport layer protocol is used for the DHCP Discover message?

Answer 7

A client that sends out a DHCP Discover message in order to receive an IP address sends out a broadcast at both layer 2 and layer 3. The layer 2 broadcast is all Fs in hex, or FF:FF:FF:FF:FF:FF. The layer 3 broadcast is 255.255.255.255, which means any networks and all hosts. DHCP is connectionless, which means it uses User Datagram Protocol (UDP) at the Transport layer, also called the Host-to-Host layer

Question 8

Which protocol is used for a Telnet connection at layer 3 and 4?

Answer 8

Telnet does use TCP and IP (TCP/IP). IP works at layer 3. Telnet uses TCP at layer 4

Question 9

Private IP addressing was specified in RFC __________

What are private IP addresses?

Answer 9

RFC 1918. These addresses can be used on a private network, but they’re not routable through the Internet

Question 10

Which of the following services use TCP? (Choose three.) Describe what each is.

A. DHCP

B. SMTP

C. SNMP

D. FTP

E. HTTP

F. TFTP

Answer 10

B, D, E. SMTP, FTP, and HTTP use TCP.

SMTP - Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (email) transmission

FTP-The File Transfer Protocol (FTP) is a standard network protocol used to transfer computer files between a client and server on a computer network.

HTTP- The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web. Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text. HTTP is the protocol to exchange or transfer hypertext.

Question 11

Which Class of IP addresses uses the pattern shown here?

Answer 11

Class C. Class C addresses devote 24 bits to the network portion and 8 bits to the host portion.

Question 12

What is the range of multicast addresses?

Answer 12

The range of multicast addresses starts with 224.0.0.0 and goes through 239.255.255.255.

Question 13

The following illustration shows a data structure header. What protocol is this header from?

Answer 13

TCP. First, you should know easily that only TCP and UDP work at the Transport layer, so now you have a 50/50 shot. However, since the header has sequencing, acknowledgment, and window numbers, the answer can only be TCP.

Question 14

If you use either Telnet or FTP, what layer are you using to generate the data?

Answer 14

Application. Both FTP and Telnet use TCP at the Transport layer; however, they both are Application layer protocols, so the Application layer is the best answer for this question

Question 15

The DoD model (also called the TCP/IP stack) has four layers. Which layer of the DoD model is equivalent to the Network layer of the OSI model?

Answer 15

Internet. The four layers of the DoD model are Application/Process, Hostto-Host, Internet, and Network Access. The Internet layer is equivalent to the Network layer of the OSI mode

Question 16

What are the ranges of the private IP addresses for Class A, B, and C?

Answer 16

The Class A private address range is 10.0.0.0 through 10.255.255.255. The Class B private address range is 172.16.0.0 through 172.31.255.255, and the Class C private address range is 192.168.0.0 through 192.168.255.255.

Question 17

What layer in the TCP/IP stack is equivalent to the Transport layer of the OSI model?

Answer 17

Host-to-Host. The four layers of the TCP/IP stack (also called the DoD model) are Application/Process, Host-to-Host (also called Transport on the objectives), Internet, and Network Access/Link. The Host-to-Host layer is equivalent to the Transport layer of the OSI model.

Question 18

How are ICMP packets used for diagnostics? How is it encapsulated?

Answer 18

ICMP can provide hosts with information about network problems. ICMP is used for diagnostics and destination unreachable messages. ICMP is encapsulated within IP datagrams, and because it is used for diagnostics, it will provide hosts with information about network problems

Question 19

What is the address range of a Class B network address in binary?

Answer 19

The range of a Class B network address is 128–191. This makes our binary range 10xxxxxx.

Question 20

Drag the steps in the DHCP process and place them in the correct order on the right.

Answer 20