What command triggers a hard reset?

• A. Clear ip bgp *
• B. Clear ip bgp (neighbor-address)
• C. Clear ip bgp (neighbor-address) out
• D. Clear ip bgp all

Answer: (A)

In BGP, a hard reset means tearing down the existing TCP session with peers and re-establishing it, which causes all routes to be re-advertised as the session restarts. The command that triggers this broadly across all peers is the one that clears every BGP session at once. By using the wildcard, you target all neighbors, forcing a complete reset of every BGP session on the router. This is the clearest way to cause a full hard reset.

The other forms either target a single neighbor or apply a reset in a more limited way (for example, affecting only outbound updates or using a syntax that doesn’t imply a global, all-peers reset). So, while they can reset something, they don’t represent the broad, full reset across all peers.