Which service assigns IP addresses automatically in a network?

• A. DNS server.
• B. Router.
• C. STP.
• D. DHCP server.

Answer: (D)

Assigning IP addresses automatically across a network is handled by a DHCP server. DHCP, or Dynamic Host Configuration Protocol, maintains a pool of IP addresses and related network settings and leases them to devices as they join the network. When a device connects, it goes through a DHCP handshake (discover, offer, request, acknowledge) to receive an IP address, subnet mask, default gateway, and DNS servers. This automation prevents manual IP configuration and avoids conflicts from duplicate addresses.

The other options don’t perform automatic IP assignment. A DNS server translates hostnames to IP addresses but doesn’t assign addresses to devices. A router routes traffic and can provide network information, but it isn’t the service that leases addresses to hosts. Spanning Tree Protocol helps prevent network loops at Layer 2 and has no role in IP address assignment.