IPv4 Addressing and Subnetting

Question 1

Address in different subnets are separated by at least one______.

Answer 1

router

Question 2

You should use one subnet for every:

Answer 2

VLAN, Point to point serial link, ethernet emulation WAN link(EoMPLS), Frame Relay PVC.

Question 3

What does subnet mask defines?

Answer 3

The size of the subnet (number of hosts a subnet contains).

Question 4

What is host bits and how does it represent subnet size?

Answer 4

(2^H) - 2 is the number of hosts(subnet size) a subnet can contain and the H is host bits. Minus 2 is for the subnet broadcasting address.

Question 5

When public IP address runs out in 2011, what are the solutions?

Answer 5

1. IPv6 with 128 bits addresses
2. Assigning a subset of a public IP network to each company, to reduce waste.
3. Network Address Translation (NAT) using Private IP networks.

Question 6

Where does subnet bits usually come from?

Answer 6

Engineers usually borrow the bits from host bits to set for subnet bits.

Question 7

Class A IP Address has ___ bits of Network
Class B IP Address has ___ bits of Network
Class C IP Address has ___ bits of Network

Answer 7

8, 16, 24

Question 8

How does devices receive their IP Address and mask assignment?

Answer 8

Dynamically by DHCP or statically through configuration.

Question 9

What are the range of IP address that are used for private IP addressing for each class?

Answer 9

Three ranges of IP addresses are designated for private use: 10.0.0.1 to 10.255.255.254(Class A), the range 172.16.0.1 to 172.31.255.254(Class B) and the range 192.168.0.1 to 192.168.255.254(Class C).

Question 10

Class A B and C are _____ IP Addresses and Class D is ________ addresses and Class E are ________.

Answer 10

Unicast, multicast, experimental.

Question 11

Large Organizations tend to use a larger size network, which class network would be ideal for this kind of large companies?

Answer 11

Class A with (2^24)-2 of hosts per network.

Question 12

What is the format of the subnet mask? or default mask?

Answer 12

In decimal 255.0.0.0
In Binary 11111111.00000000.0000000.00000000
This is an example of Class A where the first octet has 8 bits of ones representing the network and the following three octets of zeros representing the host.

Question 13

How do we find the number of subnet and valid IP hosts in a given IP address and prefix 172.15.1.1/23?

Answer 13

1. Identify the class and number of network bits: in this case class B and 8 bits
2. Identify the subnet bits and host bits: 23-8=7 subnet bits; 32-23=9 host bits.
3. 2^7= number of subnets
4. 2^9-2= number of valid host IP

Question 14

If a host sits in the same LAN as the local router, but has a different subnet, how does the router behave?

Answer 14

The router won’t forward package to the host.