Network ID Identification with Default Subnet Mask

The Network ID, often referred to as the Network Address, is a crucial part of an IP address. It uniquely identifies the specific network to which a device belongs. To determine the Network ID, we apply the subnet mask to the IP address. The subnet mask defines which part of the IP address represents the network and which part represents the host device within that network.

Analyzing the 192.168.10.51 IP Address

The IP address provided is 192.168.10.51. IP addresses are categorized into classes (A, B, C, D, E) based on their first octet. Since the first octet of 192.168.10.51 is 192, this IP address falls into Class C.

Default Subnet Mask and Network Portion

For Class C IP addresses, the standard or default subnet mask is 255.255.255.0. This mask tells us that:

• The first three octets (255.255.255) represent the Network portion.
• The last octet (0) represents the Host portion.

In the given IP address 192.168.10.51:

• The network portion is 192.168.10.
• The host portion is 51.

We can represent this using LaTeX notation:

IP Address: $192.168.10.51$

Default Subnet Mask: $255.255.255.0$

The Network ID is found by performing a bitwise AND operation between the IP address and the subnet mask. This effectively sets the host portion to all zeros, resulting in the network address.

Calculation: $192.168.10.51 \text{ AND } 255.255.255.0 = 192.168.10.0$

While 192.168.10.0 is the complete Network Address, the question asks for the specific *part* of the IP address 192.168.10.51 that identifies the network.

Identifying the Correct Network Part

Based on the default subnet mask 255.255.255.0, the network is defined by the first three octets of the IP address. These octets are 192.168.10.

Therefore, the part of 192.168.10.51 that serves as the Network ID, identifying the network segment, is 192.168.10.