What is the purpose of max-prefix configuration in protecting BGP from table floods?

• A. Improve memory efficiency by pre-filtering routes
• B. Increase convergence time to reduce churn
• C. Prevent memory exhaustion by limiting accepted routes during rapid changes
• D. Allow unlimited prefixes during floods

Answer: (C)

The main idea being tested is how a max-prefix limit acts as a guardrail to protect a BGP router from running out of memory during floods. In BGP, each neighbor’s routes are stored in the Adj-RIB-In, and during rapid changes or floods a peer can advertise a huge number of prefixes quickly. If the router accepted them all, memory and processing could be overwhelmed, leading to instability or failure. Setting a maximum number of prefixes per neighbor stops accepting more routes once the cap is reached, typically by tearing down the session or generating a warning, which prevents memory exhaustion and preserves control-plane stability. This isn’t about pre-filtering to improve efficiency, nor about increasing convergence time, and it doesn’t allow unlimited prefixes during floods.