The Dynamic Host Configuration Protocol (DHCP) is a protocol that automatically assigns IP addresses and other network configuration parameters to network devices12. DHCP uses a client-server model, where a DHCP client requests an IP address from a DHCP server, and the DHCP server responds with an IP address and other information34.
When a DHCP client and server are on the same physical network, the DHCP client broadcasts a DHCPDISCOVER message to find a DHCP server, and the DHCP server replies with a DHCPOFFER message containing an IP address offer34. The DHCP client then broadcasts a DHCPREQUEST message to request the IP address, and the DHCP server replies with a DHCPACK message to acknowledge the IP address assignment34.
When a DHCP client and server are not on the same physical network, a DHCP relay is used to forward the DHCP messages between them56. A DHCP relay is a network device, such as a router or a switch, that listens for DHCP broadcast messages on one network interface and relays them to another network interface where the DHCP server is located56. The DHCP relay also adds the IP address of the network interface where the DHCP client is located to the DHCP messages, so that the DHCP server can determine which pool of IP addresses to use for the DHCP client56.
The other options are not related to forwarding requests and replies between a DHCP server and client. A DHCP lease is the duration of time that a DHCP server assigns an IP address to a DHCP client78. A DHCP scope is a range of IP addresses that a DHCP server can assign to DHCP clients on a specific network segment78. A DHCP range is a subset of a DHCP scope that defines the start and end IP addresses that a DHCP server can assign to DHCP clients .
Therefore, the best answer is A. Relay, which would be used to forward requests and replies between a DHCP server and client.
References:
1: CompTIA Network+ N10-008 Certification Study Guide, page 215
2: CompTIA Network+ Certification Exam Objectives, page 9
3: [What is Dynamic Host Configuration Protocol (DHCP)? - Definition from WhatIs.com]
4: [Dynamic Host Configuration Protocol (DHCP) | CompTIA IT Certifications]
5: CompTIA Network+ N10-008 Certification Study Guide, page 216
6: [What is DHCP Relay? - Definition from Techopedia]
7: CompTIA Network+ N10-008 Certification Study Guide, page 217
8: [What is DHCP Lease? - Definition from Techopedia]
: [What is DHCP Range? - Definition from Techopedia]
: [DHCP Range | CompTIA IT Certifications]
