List the types of IP access lists (numbered standard, numbered extended, named standard, named extended) that can be enabled to prevent Telnet access into a router. What commands would be used to enable this function, assuming that access-list 2 was already configured to match the right packets?
Any type of IP access list can be enabled to prevent vty access. The command "line vty 0 4", followed by "ip access-class 2 in", enable the feature using access list 2. Because ACLs used for preventing Telnet access into a router check only the source IP address, there is no need for an extended ACL in this case, anyway.