CPSA Port Numbers with Services and Protocols Practice Test

The Daytime service uses a simple protocol that returns a human-readable current date and time, and it runs over either TCP or UDP on port 13. That makes port 13 the correct choice. The other ports correspond to different services: port 9 is the discard service (it just drops data), port 67 is used by the DHCP server, and port 135 is the RPC endpoint mapper used by various Windows services. So, for the Daytime service, port 13 is the appropriate one.