"no exec" will disable access to a line. It is used if we want to allow only outgoing session (and disable incoming session) so this command will block all console port access. There is no "exec 0 0" command. We can only find the "exec prompt" command in IOS Version 15.4(2)T4. The most similar command is "exec-timeout 0 0" command, which is used to prevent Telnet/SSH sessions from timing out.