What is the maximum size of an IPv4 header?

The correct maximum size of an IPv4 header is indeed 60 bytes. The base size of the IPv4 header is 20 bytes, which includes the essential fields necessary for the packet to be processed by networking equipment. However, the header can accommodate additional options that increase its size.

The IPv4 header is defined by a set number of fields, each of which has a specific function, such as source and destination addresses, version, header length, type of service, total length, identification, flags, fragment offset, time-to-live, protocol, header checksum, and options. The options field allows for added functionality beyond the base header specification and can increase the total header size up to a maximum of 60 bytes.

When considering the maximum size of the header, it is important to account for the fact that options can add up to 40 bytes of additional data to the standard 20-byte header. Thus, the total can reach 60 bytes, making that the correct choice for the maximum size of an IPv4 header.