Enabling a mask parameter in a BGP network command allows what?

• A. It determines authentication method for BGP sessions
• B. It enables automatic route summarization
• C. It allows BGP to use classless prefixes; it can advertise subnets and supernets
• D. It restricts advertisement to the classful network

Answer: (C)

The concept being tested is how BGP handles subnetting and prefix specificity. When you enable a mask parameter in a BGP network command, you’re enabling classless routing by allowing prefixes to be advertised with explicit subnet masks rather than sticking to the default classful boundary. This lets BGP carry and propagate more granular routes, meaning subnets can be advertised and learned, and supernets can be configured as needed. This CIDR/classless capability is what makes precise routing possible in modern networks, including discontiguous networks and variable-length subnetting.

The other options don’t describe this behavior. Authentication methods for BGP sessions are configured separately and aren’t controlled by a mask parameter. Route summarization is a distinct feature (auto-summarization or manual summarization) and isn’t inherently tied to enabling a mask. Finally, the mask enables more precise, not more restricted, advertisement—advertising only the classful network would be the opposite of what a mask parameter provides.