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Differentiate between a subnet mask and a default gateway.

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Subnet Mask:

Definition:

A subnet mask is a 32-bit number that divides an IP address into network and host portions. It is used to identify the network and host portions of an IP address.

Structure:

A subnet mask consists of two parts: the network portion (contiguous set of 1s) and the host portion (contiguous set of 0s). The combination of these two parts creates a binary number that is 32 bits long.

Example:

  • IP Address: 192.168.1.10
  • Subnet Mask: 255.255.255.0 (or in binary: 11111111.11111111.11111111.00000000)

In this example, the first 24 bits are dedicated to the network, and the last 8 bits are for hosts.

Purpose:

The subnet mask helps devices determine whether an IP address is on the local network or a remote network. When a device needs to communicate with another device, it checks whether the destination IP address is in the same subnet. If it is, the communication is considered local; otherwise, it routes the communication through a router.

Default Gateway:

Definition:

A default gateway is a device (usually a router) on a network that serves as an entry and exit point for network traffic. It is used when a device needs to communicate with a device on a different network.

Role:

When a device wants to communicate with a destination outside its local subnet, it forwards the data packet to the default gateway. The default gateway is responsible for routing the packet to the appropriate destination network.

Configuration:

Devices on a network need to be configured with the IP address of the default gateway. This is typically done manually or through DHCP (Dynamic Host Configuration Protocol) during the device's network setup.

Example:

  • IP Address: 192.168.1.10
  • Subnet Mask: 255.255.255.0
  • Default Gateway: 192.168.1.1

In this example, if the device wants to communicate with a device outside the 192.168.1.0/24 network, it sends the data packet to the default gateway (192.168.1.1).

Relationship:

  • The subnet mask is used to determine whether a destination IP address is on the local network or a remote network.
  • The default gateway is used to route traffic from the local network to remote networks.