In Internet Protocol version 4 IPv4 addressing, for what purpose is the special address 255.255.255.255 used?

Introduction / Context:
IPv4 includes several special addresses with predefined meanings. One of the most recognisable is 255.255.255.255, which contains all bits set to 1 in the address field. This address is not assigned to any single host. Instead, it serves a special broadcast function. Understanding its purpose is important when studying addressing, routing, and network configuration. This question asks what 255.255.255.255 is used for in IPv4 networks.

Given Data / Assumptions:

• IPv4 addresses consist of 32 bits, sometimes interpreted as network and host portions depending on the subnet mask.
• Certain addresses are reserved, such as network addresses, broadcast addresses, and loopback addresses.
• 255.255.255.255 has all 32 bits set to 1.
• The question focuses on the single address 255.255.255.255, not on general subnet broadcast addresses.

Concept / Approach:
The address 255.255.255.255 is defined as the limited broadcast address. When a host sends a packet with this destination address, the packet is delivered to all hosts on the local network segment but is not routed beyond that local segment. Routers normally do not forward packets with this destination. This broadcast is useful for functions such as address discovery and certain configuration protocols on the local network. The correct option must identify 255.255.255.255 as a broadcast address for the local subnet and not confuse it with gateways, private addresses, or invalid addresses.

Step-by-Step Solution:
Step 1: Recall that broadcast addresses allow a host to send one packet that all local hosts can receive. Step 2: Recognise that subnet specific broadcast addresses have host bits set to 1 within that subnet, while 255.255.255.255 is a special broadcast to all hosts on the local network. Step 3: Understand that routers usually do not forward this address, which is why it is called a limited broadcast. Step 4: Evaluate option a, which correctly calls 255.255.255.255 the limited broadcast address to all hosts on the local network segment. Step 5: Reject other options that describe it as a default gateway, private address, or invalid address.

Verification / Alternative check:
Network textbooks and standards documents refer to 255.255.255.255 as the limited broadcast. Packet capture tools like Wireshark can show broadcast packets, such as DHCP discovery messages, that often use this address as the destination. The fact that routers drop these packets for forwarding confirms that the broadcast is limited to the local segment. This matches the description given in option a.

Why Other Options Are Wrong:
Option b is incorrect because default gateway addresses are normal host addresses on the local subnet, not the all ones broadcast address. Option c is wrong because private address ranges are specific blocks like 10.0.0.0/8 or 192.168.0.0/16, not 255.255.255.255. Option d is incorrect because the address is valid and used for broadcasting, even though it is never assigned to an individual host interface.

Common Pitfalls:
Students sometimes confuse 255.255.255.255 with subnet broadcast addresses such as 192.168.1.255. While both are broadcast addresses, the latter is specific to a particular subnet, while 255.255.255.255 is a special limited broadcast applicable to the local segment regardless of the configured subnet mask. Remembering this distinction helps when analysing broadcast traffic and configuring routers to filter or handle broadcasts appropriately.

Final Answer:
The IPv4 address 255.255.255.255 is the limited broadcast address used to send a packet to all hosts on the local network segment.