Which three of the following describe the Border Gateway Routing Protocol (BGP) configuration on a...

It supports a 4-byte autonomous system number: BGP on a Tier-0 Gateway supports 4-byte AS (Autonomous System) numbers, which are necessary for larger routing domains.

Can be used as an Exterior Gateway Protocol: BGP is commonly used as an Exterior Gateway Protocol to establish routing between different autonomous systems (AS).

BGP is enabled by default: On a Tier-0 Gateway, BGP is typically enabled by default, allowing administrators to configure it for external routing.