You want to set a static IP address on Port A of a Cisco TelePresence MCU 5300. You navigate to Network >
Port A and configure the device with IP address 192.168.1.43, subnet mask 255.255.255.0, and default
gateway 192.168.1.1. However, the device’s IP address does not change.
Which of the following statements correctly diagnoses the problem?

A.
You must change the subnet mask.

B.
You must change the default gateway.

C.
You must reboot the Cisco MCU 5300.

D.
You must set the IP configuration to Manual.

E.
You must change the IP address by using the CLI.

F.
Port A cannot be configured with a static IP address.

Explanation:
You must set the IP configuration to Manual. If the IP configuration is set to Automatic via DHCP, the Cisco
TelePresence multipoint control unit (MCU) 5300 will ignore a static IP address configuration. By default, a
Cisco MCU 5300 is configured to receive its IP configuration from a Dynamic Host Configuration Protocol
(DHCP) server.
The Cisco MCU 5300 has two Ethernet interfaces: Port A and Port B. You can change the IP address of either
port by using the command-line interface (CLI), but you are not required to do so. To configure a static IP
address for Port A, issue the static A ip-address subnet-mask [default-gateway] command. To configure Port A
to receive its IP configuration from a DHCP server, issue the dhcp -4 A command. To configure Port B similarly,
change the A keyword to B.
The subnet mask and default gateway in this scenario are probably configured correctly. Changing neither the
subnet mask nor the default gateway will cause the device’s IP address to change.
You need not reboot the Cisco MCU 5300 after configuring a static IP address. The static IP address will takeeffect as soon as it is configured as long as the IP configuration is set to Manual.

Cisco: Cisco TelePresence MCU 5300 Series, Administration guide: Configuring network and system settings
(PDF)