A network administrator is configuring a Cisco IOS router to act as a DHCP relay agent for host clients residing on VLAN 25 (). The centralized DHCP server is located at IP address in a different subnet connected off interface GigabitEthernet0/0/0. Which statements regarding the operation and Cisco IOS configuration of the DHCP relay agent are correct? (Select TWO.)
- The `ip helper-address 10.100.1.50` command must be configured under the client-facing subinterface (GigabitEthernet0/0.25).Cevap
- The router inserts the client-facing interface IP address into the Gateway IP Address (`giaddr`) field of the DHCP header before unicasting the request to the server.Cevap
- CThe `ip helper-address 10.100.1.50` command must be configured under the egress interface (GigabitEthernet0/0/0) facing the server.
- DThe router retransmits the client broadcast DHCP Discover frame as a layer 2 broadcast frame out the egress server interface.
Cevap
The correct statements are that the `ip helper-address 10.100.1.50` command must be configured on the client-facing interface (GigabitEthernet0/0.25), and that the router populates the Gateway IP Address (`giaddr`) field with its client-facing interface IP address when unicasting the request to the server.
Configuring `ip helper-address 10.100.1.50` on the client-facing gateway interface enables the router to listen for incoming client DHCP broadcasts. When relaying the request to the DHCP server as a unicast IPv4 packet, the router populates the `giaddr` (Gateway IP Address) field in the DHCP payload with the IP address of that client-facing interface, allowing the DHCP server to identify which address pool to select from.
Adım Adım Çözüm
Anahtar Kavram
DHCP Relay Agent Operation and Interface Configuration