Subnet Masks and Network Classes

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Questions and Answers

What is the primary purpose of a subnet mask?

To increase the speed of data transmission

To encrypt data packets during transmission

To track the number of devices in a network

To identify which bits in an IP address represent the network/subnet (correct)

How many bits are borrowed from the host portion to create four subnets in a Class C network?

3 bits

2 bits (correct)

1 bit

4 bits

If a Class C network is subdivided into four subnets, what is the new subnet mask?

255.255.255.224 (correct)

255.255.255.240

255.255.255.252

255.255.255.128

What is the effect of borrowing bits from the host portion of an IP address?

It decreases the number of available IP addresses for hosts Signup and view all the answers

Given a network address of 10.0.0.0, how many bits are required to create 8 subnets?

3 bits Signup and view all the answers

For a router-to-router link that requires only two host addresses, how many host bits are typically needed?

2 host bits Signup and view all the answers

What components make up the complete subnetting process?

Network address, host address, and subnet mask Signup and view all the answers

If 2 bits are used for subnetting in a Class C IP address, what is the configuration of the subnet mask?

/26 Signup and view all the answers

What does the notation 192.168.12.0 indicate?

It is a reserved IP address for private networks Signup and view all the answers

What is the result of applying the formulas for calculating the number of subnets and hosts per subnet?

Determining the configurations of subnets and their capacities Signup and view all the answers

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

255.255.255.252 Signup and view all the answers

How does a subnet mask affect data packet routing within a LAN?

It determines if the packet is sent to the gateway or stays within the LAN. Signup and view all the answers

If a computer in the LAN has the IP address 172.16.35.3 and uses a subnet mask of 255.255.255.0, which IP address is not in the same subnet?

172.16.34.15 Signup and view all the answers

What does the subnet mask 255.255.255.0 indicate about the corresponding IP address range?

Only addresses 172.16.35.0 to 172.16.35.255 are valid within the LAN. Signup and view all the answers

What is the purpose of 'ANDing' the subnet mask with the destination address?

To determine if the destination is in the same subnet. Signup and view all the answers

Which of the following correctly describes how subnetting can impact a network?

It provides better security by isolating traffic. Signup and view all the answers

What does the term 'borrowing bits' mean in the context of subnetting?

Using bits from the host portion to create additional subnetworks. Signup and view all the answers

Which of the following statements about subnet masks is true?

Subnet masks are used to classify hosts within the same network. Signup and view all the answers

If a data packet has a destination IP of 172.16.34.15 and is using the subnet mask 255.255.255.0, what action will be taken?

The packet will be sent to the LAN's gateway. Signup and view all the answers

What is the maximum number of hosts that can be accommodated by a subnet mask of 255.255.255.252?

2 Signup and view all the answers

Study Notes

Subnet Masks

Subnetting is a technique used to divide a network into smaller networks (subnets).
Subnets are created using subnet masks.
The subnet mask identifies the bits in the IP address that represent the network/subnet portion of an IP address.
Subnets are created by borrowing bits from the host portion of the IP address.
The network portion and the new subnet bits define the new subnet.
Routers use this information to forward data packets to the correct subnet.

Network Classes and Subnets

Class A networks have a network portion of 8 bits, a subnet portion, and a host portion.
Class B networks have a network portion of 16 bits, a subnet portion, and a host portion.
Class C networks have a network portion of 24 bits, a subnet portion, and a host portion.
To create subnets from a particular class of network, bits are borrowed from the host portion.

Calculating Subnets and Hosts

The number of subnets created equals 2^x, where x is the number of bits borrowed from the host.
The number of hosts per subnet equals 2^y-x, where y is the number of host bits for the class of network, and x is the number of bits borrowed to generate the subnets.

Usable Hosts/Subnet

The number of usable hosts per subnet is calculated as 2^(y-x) - 2. This is because the network address and broadcast address are not usable host addresses.

Subnet Mask Considerations

Each subnet has a network address and a broadcast address.
The subnet mask is used to distinguish between network, subnet, and host bits in an IP address.
A bit in the subnet mask set to 1 indicates a network or subnet bit; a 0 indicates a host bit. The subnet mask is a series of 1s followed by a series of 0s.
The subnet mask is used to direct data packets within a network, and to determine if the intended destination is within the same subnet or outside of it.
The gateway's IP address is the interface on a layer-3 switch or router.

Example Calculations

Various examples of calculating subnets based on specific network and host bit counts for a class of network are provided.
Example of how to determine the proper subnet mask, considering these examples and calculations.

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Description

This quiz covers the fundamentals of subnetting, including the use of subnet masks to create subnets from IP addresses. It explains the characteristics of Class A, B, and C networks and how to calculate subnets and hosts effectively. Test your understanding of these key networking concepts!