Section: Service-related Knowledge

The show ip interface brief command provides a concise summary of the status and IP addressing configuration of interfaces on a Cisco router or switch. Here's what it displays:
Interface: The name of the interface (e.g., FastEthernet0/0, GigabitEthernet1/1).
IP Address: The Layer 3 IP address assigned to the interface (if any).
OK? Indicates the IP layer status of the interface (YES if operational, NO if not).
Method: How the IP address was configured (manual or DHCP).
Status: The Layer 1 status of the interface (up or down).
Protocol: The Layer 2 status of the interface (up or down).
Why other options are incorrect:
Layer 2 address: The show ip interface brief command does not directly display Layer 2 (MAC) addresses. You can use the show interface <interface-name> command for that.
Keepalive: Keepalives are used in some routing protocols but are not generally reflected in the output of the show ip interface brief command.
Encapsulation type: Encapsulation information is also not typically included in the show ip interface brief output.
Reference:
Cisco IOS show ip interface brief command: [invalid URL removed]
Example output of show ip interface brief: https://www.cisco.com/E-Learning/bulk/public/tac/cim/cib/using_cisco_ios_software/cmdrefs/show_ip_interface.

The correct IPv6 address notation follows the format of eight groups of four hexadecimal digits, separated by colons. The address must have exactly eight groups unless it uses the double colon (::) to represent consecutive groups of zero value. The double colon can only appear once in an address to avoid ambiguity.
Option A is incorrect because it includes a subnet mask (/128) which is not part of the actual address notation. Option B is incomplete as it does not contain enough groups and ends with a single colon. Option C has too many groups (nine instead of eight) and is therefore not a valid IPv6 address. Option D is the correct notation with eight groups of four hexadecimal digits, where necessary leading zeros are included.
Reference:
IPv6 Address Types, Notation, and Structure Explained1.
IPv6 address formats - IBM2. =========================

Section: General Networking Knowledge