Subnetting

Question 1

How do you determine if the IP Address is in the same subnet?

Answer 1

1. Determine subnet Address of the source (self) IP Address
   2 .Determine the subnet address of destination IP Address
2. If both match the destination node is the same subnet

Question 2

Given this IP and Subnet Mask, what is the resulting dotted decimal and binary output?

IP Address(Dotted Decimal/Binary): 192.168.10.130/ 110000000 10101000 00001010 10000010
Subnet Mask(Dotted Decimal/Binary): 255.255.255.0/ 11111111 1111111 1111111 00000000

Answer 2

• Do bit-wise AND operation between IP address and Mask
• The result is the subnet address or ID

Result(Dotted Decimal/Binary): 192.168.10.0/ 11000000 10101000 00001010 00000000

Question 3

What is CIDR and what does it do?

Answer 3

Classless Inter-Domain Routing

1. Developed to slow the exhaustion of IP Addresses
2. Based on assigning IP addresses on criteria other than octet boundaries

Example: 200.16.1.48/25 (CIDR notation)

Question 4

How do you get a Subnet Address?

Answer 4

1. A Network is identified by the first of first few octets

2. A TCP/IP host must have a nonzero host identifier

Question 5

How do you get a Broadcast Address?

Answer 5

When the entire host portion of an IP Address is all binary ones

Examples: 190.255.255.255 and 199.192.65.63

Question 6

What do Broadcast Types do/what are they?

Answer 6

1. Broadcasts for any subnet
2. Use the IP Address 255.255.255.255
3. A Router does not propagate flooded broadcasts because they are considered local

Question 7

Directed Broadcasts

Answer 7

1.For specific subnets
2. Router can forward directed broadcasts
Example: a packet sent to the class B address 129.30.255.255 would be a broadcast network for 129.30.0.0

Question 8

What does subnetting do?

Answer 8

Divides the major network IP block into smaller blocks

Example:
Major network block (class C)
192.168.1.0 – 192.168.1.255 (256 addresses)
Now divided into 2 sub-blocks (128 addresses)
192.168.1.0 – 192.168.1.127(128 Addresses)
192.168.1.128 – 192.168.1.255 (128 Addresses)
Now divided into 4 sub-blocks (subnets)
192.168.1.0 – 192.168.1.63 (64 Addresses)
192.168.1.64 – 192.168.1.127(64 Addresses)
192.168.1.128 – 192.168.1.191(64 Addresses)
192.168.1.192 – 192.168.1.255(64 Addresses)

Question 9

Reasons for subnetting?

Answer 9

1. To match the physical layout of an organization
2. To match the administrative structure of the organization
3. Optimized network performance
4. Simplified management
5. To plan for future growth
6. To reduce network traffic