What is the purpose of the subnet mask when used with an IP address?

What is the purpose of the subnet mask when used with an IP address?

• A. to determine the subnet to which the host belongs
• B. to determine the default gateway for the host
• C. to determine the host's MAC address
• D. to encrypt the IP address for secure transmission

Answer: (A)

Subnet masks identify which part of an IP address is the network address. By masking an IP with the subnet mask, you reveal the network portion and determine the subnet the device belongs to. This helps devices decide whether a destination is on the same local subnet or must be reached through a router. For example, with 192.168.1.10 and 255.255.255.0, the network is 192.168.1.0, so the host sits on the 192.168.1.0 subnet. The subnet mask does not determine the default gateway, nor does it relate to a MAC address or encryption; its role is to indicate subnet membership and guide local versus remote routing.

Subnet masks identify which part of an IP address is the network address. By masking an IP with the subnet mask, you reveal the network portion and determine the subnet the device belongs to. This helps devices decide whether a destination is on the same local subnet or must be reached through a router. For example, with 192.168.1.10 and 255.255.255.0, the network is 192.168.1.0, so the host sits on the 192.168.1.0 subnet. The subnet mask does not determine the default gateway, nor does it relate to a MAC address or encryption; its role is to indicate subnet membership and guide local versus remote routing.