What must an interface be configured with?

• A. An IP Address, a Subnet Mask, and Activated with the No Shutdown Command
• B. An IP Address and a Default Gateway
• C. A DNS Server and an NTP Server
• D. A MAC Address and a VLAN Tag

Answer: (A)

An interface can participate in IP networking only when it has an IP address paired with a subnet mask and is active. The IP address gives the device a network identity on the local segment, while the subnet mask defines which portion of that address identifies the network versus the host, enabling correct routing, ARP resolution, and communication with other devices on the same network. The interface must be brought up (no shutdown) to move from a administratively down state to a usable, forwarding state. DNS and NTP settings are useful for name resolution and timekeeping but are not required for the interface itself to function at the IP layer. A MAC address is fixed by the hardware, and a VLAN tag is only needed when the interface is placed into a specific VLAN on a trunk; neither is required for basic IP operation.