TCP/IP Network Model

Question 1

Name four application layer protocols in the TCP/IP network model.

Answer 1

1. HTTPS (secure web)
2. SSH (secure shell)
3. FTP (file transfer)
4. SMTP (email delivery)

Question 2

What are the two protocols used in the transport layer of the TCP/IP network model?

Answer 2

1. TCP
2. UDP

Question 3

What layer of the TCP/IP network model uses IPv4 and IPv6 protocols?

Answer 3

Internet layer, or Network Layer

Question 4

What two pieces of information form a socket?

Answer 4

IP address and service port.

Question 5

Which layer of the TCP/IP network model provides the connection to physical media?

Answer 5

The Link or Media Access Layer.

Question 6

What three layers of the OSI network model correspond to the Application layer of the TCP/IP model?

Answer 6

Application (7), Presentation (6), and Session (5).

Question 7

What two layers of the OSI network model correspond to the Link layer of the TCP/IP model?

Answer 7

The Data Link and Physical layers.

Question 8

In RHEL 7 and later, what prefixes are assignes to network interfaces for ethernet, WLAN, and WWAN?

Answer 8

en, wl, and ww.

Question 9

In RHEL 7 and later, what characters are used to represent network interface types for onboard, PCI hotbus slot, and PCI on bus M in slot N

Answer 9

o

N,

s

N,

p

M

s

N

Question 10

How many bits are assigned as the network prefix for Class A, Class B, and Class C networks?

Answer 10

Class A - 8 bits
Class B - 16 bits
Class C - 24 bits

Question 11

What is CIDR?

Answer 11

Classless Inter-Domain Routing
The newer network addressing specification, which allows for a variable number of bits in the network prefix of an IPv4 address.

Question 12

What is a network mask

Answer 12

A binary mask whose length indicates the number of bits assigned to the network prefix that identifies a subnet.

Question 13

What two forms of expressing a network mask are used?

Answer 13

1. CIDR notation (192.168.0.1/24)
2. Four 8 bit octets (255.255.255.0)

Question 14

What address within a subnet is reserved for the network address?

Answer 14

The lowest possible address, where the host number is all binary zeros.

Question 15

What address within a subnet is reserved for the broadcast address?

Answer 15

The highest possible address, where the host number is all binary ones.

Question 16

What address is commonly used as the gateway address of a subnet?

Answer 16

The first available host number, which the binary number is all zeros except for a ‘1’ in the last bit.

Question 17

What are the steps to find the addresses associated with a subnet, given a host’s address and mask?

Answer 17

Host address - 172.16.181.23/19
Mask - 255.255.224.0
1. Find the Inverse Mask - 0.0.32.255
2. Find the Network address start numbers -
172.16.(0, 32, 64, 96, 128, 160, 192, 224).0
3. Find the Network address that the given host falls under - 172.16.160.0
4. Find the Broadcast address - 172.16.191.255
5. Find the Host address range -
172.16.160.1 to 172.16.191.254

Question 18

Find the network address, broadcast address, and network host rnage for the subnet 192.168.255.57/23

Answer 18

Host: 192.168.255.57
Subnet Mask: 255.255.254.0
1. Inverse Mask: 0.0.1.255
1. Network addresses: 192.168.254.0, 192.168.255.0
1. Broadcast address: 192.168.255.255
1. Host address range: 192.168.255.1 to 192.168.255.254

Question 19

How many bits are there in an IPv6 address?

Answer 19

128 bits expresses in eight groups of four hexadecimal nibbles (half bytes).
2001:0db8:0000:0010:0000:0000:0000:0001

Question 20

What are the rules for simplifying an IPv6 address?

Answer 20

1. Remove all leading zeros from groups.
2. Replace one or more conecutive groups of zeros with a double colon (::)
3. When including a port number with an IPv6 address always wrap the IP address portion in [] to avoid the port being confused with the address. (i.e. [2001:db8:0:10::1]:80

Question 21

What does Red Hat recomend as tips for simplifying consistantly readable IPv6 addresses?

Answer 21

• Supress leading zeros in a group.
• Use a two-colon (::) block to shorten the address as much as possible.
• If an address contains two seperate sections of two or more groups with all zeros, reduce the leftmost section to :: and the rightmost section to :0: for each group. (i.e. shorten 2001:0000:0000:0000:0db8:0000:0000:0000 to 2001::0db8:0:0:0
• Although it is allowed, do not use :: to shorten a single group of zeros (:0000:). Use :0: instead and leave :: for multiple groups of all zeros.
• Always use lowercase letters for hexadecimal characters.

Question 22

In an IPv6 address, how many bits represent the network protion and the interface portion of the address?

Answer 22

64 bits each.

Question 23

What is the typical IPv6 address for a localhost?

Answer 23

::1/128

Question 24

What is the IPv6 network address reserved for multicast?

Answer 24

ff00::/8

Question 25

What is the IPv6 network address reserved for link-local addresses?

Answer 25

fe80::/10

Question 26

What is an IPv6 link-local address?

Answer 26

An unroutable address that the system uses to talk to other systems on the same network link.

Question 27

What are the two methods of IPv6 dynamic address configuration?

Answer 27

DHCPv6 and SLAAC (StateLess Address AutoConfiguration)

Question 28

In what file does Linux store the hostname to IP address information for name resolution?

Answer 28

/etc/hosts