Subnetting and IP Address Classes

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Questions and Answers

What is the primary purpose of a subnet mask?

To identify the network and subnet bits in an IP address (correct)

To create additional IP addresses

To enhance network speed

To secure data transmission

How many bits need to be borrowed to create four subnets?

4 bits

3 bits

2 bits (correct)

1 bit

If a Class C network is partitioned into four subnets, what is the resulting subnet mask?

255.255.255.0

255.255.255.128

255.255.255.192 (correct)

255.255.255.224

What is the result of borrowing bits from the host part of an IP address?

Decreased number of hosts per subnet Signup and view all the answers

If 3 bits are borrowed from the host portion for subnetting, how many subnets can be created?

8 subnets Signup and view all the answers

What is indicated by the two Most Significant Bit (MSB) positions borrowed from the host and network portions?

They are included in the subnet mask Signup and view all the answers

What is the total number of usable hosts per subnet when a subnet uses 3 bits for hosts?

30 usable hosts Signup and view all the answers

If only two host addresses are needed for a router-to-router link, what subnet mask would likely be used?

255.255.255.252 Signup and view all the answers

What equation can be applied to calculate the number of hosts per subnet?

$2^{(borrowed bits)} - 2$ Signup and view all the answers

What is the effect of subnetting on the overall number of IP addresses in a network?

Decreases the total number of available IP addresses Signup and view all the answers

What subnet mask is needed for a router-to-router link requiring only two host addresses?

255.255.255.252 Signup and view all the answers

What does a subnet mask of 255.255.255.0 indicate about IP addresses in a LAN?

All addresses between 172.16.35.0 and 172.16.35.255 can communicate directly. Signup and view all the answers

How can you verify if a destination IP address is in the same subnet as the LAN?

By 'ANDing' the subnet mask with the destination address. Signup and view all the answers

What is typically the physical network interface for gateway IP addresses in a LAN?

A layer 3 switch or a router Signup and view all the answers

What does the first three octets in the subnet mask 255.255.255.0 signify?

They must match to indicate the same subnet. Signup and view all the answers

What is a common misconception about subnetting with a subnet mask of 255.255.255.0?

It allows for 256 devices to connect. Signup and view all the answers

In the example provided, what does the destination IP address 172.16.34.15 indicate when using a subnet mask of 255.255.255.0?

It is outside the subnet of 172.16.35.0. Signup and view all the answers

How does borrowing bits in subnetting affect available hosts in a subnet?

It decreases the number of available hosts. Signup and view all the answers

If a network uses 255.255.255.128 as a subnet mask, what is the potential number of subnets?

2 subnets Signup and view all the answers

What is the effect of using a subnet mask with fewer host bits?

Fewer subnets can be created. Signup and view all the answers

Study Notes

Subnet Masks

Subnetting is a technique to divide networks into subnets.
Subnets are created using subnet masks.
Subnet masks identify bits in IP addresses used to signify network/subnet portions.

Subnetting

Subnetting breaks down networks into smaller subnets.
Subnets are created by borrowing bits from the host portion of IP addresses.
The new subnet bits, along with the network portion, define the new subnet.
Routers use this information to forward data packets to the correct subnets.

IP Address Classes (A, B, C)

Class A networks have a variable network portion (more host bits).
Class B networks have a larger network portion.
Class C networks have the largest network portion (least amount of host bits).
Octet values are used to divide the IP address into pieces.

Subnet Creation

Subnets are formed by borrowing bits from the host portion using the formula:
- Number of subnets = 2^x where x = Number of borrowed bits
Subnets reduce available host bits reducing the total number of hosts in the subnet.
Formulas for host/subnet calculation:
- Number of hosts/subnet = 2^y-x where y = number of original bits in the host portion, and x = number of borrowed bits

Usable Hosts/Subnet

Subnets have network and broadcast addresses.
A formula accounts for these when calculating usable hosts.
Usable hosts/subnet = 2^(y-x) - 2

Applying Subnet Masks

Subnet masks use logical AND operations (1s and 0s.)
1s in the mask indicate the IP address bits passed during forwarding.
0s in the mask prevent forwarding those bits.
Output depends on whether the subnet mask bit is set to 1 or 0.

Example Calculation (192.168.12.0)

Breaking down the 192.168.12.0 network into four subnets involves borrowing two host bits.
- Therefore x = 2 and y = 8 (standard for class C)
- Using calculating formulas:
- Number of subnets =2² = 4
- Number of hosts/subnet = 2^8-2 = 64

Subnet Mask Determination

To find the specific mask, you need to determine the number of host bits being used.
The most significant bits are borrowed from the original host section of the IP address .

Controlling Data Flow

Subnet masks help direct data within networks.
They check if the destination IP address is on the same or different LAN.
Data packets routed to the gateway address.
Gateway address in on a different LAN.
Gateway address is on a layer 3 switch or a router.

Examples and Summary

Specific examples demonstrate how to apply subnetting to various IP address classes.
This section has demonstrated how subnets and subnet masks control data flow within computer networks.
Examples guide the reader through determining the number of hosts in a specific subnet.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on subnetting techniques, subnet masks, and IP address classes. This quiz covers how subnets are created by borrowing bits from host portions and the characteristics of Class A, B, and C networks. A great way to solidify your understanding of IP addressing!