How many bits long is the 'Destination IP Address' field in the IPv4 header?

The 'Destination IP Address' field in the IPv4 header is 32 bits long. This is because IPv4 addresses are represented in a 32-bit binary format. Each bit in this address can either be 0 or 1, allowing for a total of 2^32 possible unique addresses, which translates to approximately 4.3 billion unique IP addresses.

Understanding the length of the destination address is crucial in networking, as it determines how devices on the network identify each other. When data packets are transmitted, the destination IP address informs routers and switches where to send the packets, ensuring they reach the correct endpoint.

Knowledge of these details helps in grasping how IP addressing works within the broader context of networking, including the implications for subnetting and the scalability of network design. Other lengths provided in the options do not accurately reflect the standard size of IPv4 addresses, thus reinforcing the uniqueness of the 32-bit format.