Which protocol is not directly related to IP address management?

The correct answer focuses on the relationship between protocols and IP address management. SMTP, or Simple Mail Transfer Protocol, is primarily used for sending and receiving email across the Internet. It does not have a role in managing or allocating IP addresses, which is the essence of IP address management.

In contrast, DHCP (Dynamic Host Configuration Protocol) is explicitly designed for obtaining IP address information automatically, allowing devices to connect to a network without needing manual IP configuration. ARP (Address Resolution Protocol) works to map IP network addresses to the hardware addresses used by a data link protocol, which is crucial for the operation of networks that use IP addresses. ICMP (Internet Control Message Protocol) is used primarily for error handling and diagnostics within an IP network but does not manage IP addresses themselves.

Therefore, while DHCP, ARP, and ICMP are integral to network operations involving IP addressing, SMTP serves a different purpose in the broader context of network protocols, which makes it the correct choice.