Which two of the following are functions of the BGP update message?

The function of withdrawing routes that are no longer valid is a core component of the BGP update message. When a router determines that a previously advertised route is no longer reachable or valid, it generates an update message specifically to withdraw that route from its peers. This ensures that all BGP peers maintain an accurate view of the routing information and can make informed routing decisions based on the most current valid routes.

Furthermore, BGP uses that same update message mechanism to send routing information to its peers, reinforcing the critical role of updates in both adding and removing routes in the BGP routing table.