What is the minimum value of the IHL field in the IPv4 header?

The minimum value of the IHL (Internet Header Length) field in the IPv4 header is 5. The IHL is expressed in 32-bit words, and the minimum size of the IPv4 header is 20 bytes, which corresponds to 5 32-bit words (since 20 bytes divided by 4 bytes per word equals 5).

This IHL value indicates the number of 32-bit words in the header and is crucial for the receiving systems to know where the actual data begins. If the header were smaller than 20 bytes, it wouldn't be able to convey sufficient information about routing, addressing, and packet control.

Understanding the role of the IHL field is essential for interpreting how the IPv4 protocol packages data, making it a foundational concept in computer networking.