Which command only announces the 1.2.3.0/24 network out of FastEthernet 0/0?

A distribute list is used to filter routing updates either coming to or leaving from our router. In this case, the “out” keyword specifies we want to filter traffic leaving from our router. Access-list 2 indicates only routing update for network 1.2.3.0/24 is allowed (notice that every access-list always has an implicit “deny all” at the end).