What transmission can you use to check the availability of a service on a network?

To check the availability of a service on a network, you can use the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP) depending on the service. For instance, sending a TCP SYN packet to a specific port can help determine if a TCP service is listening. Alternatively, using a UDP packet can be effective for services that rely on this protocol, although it may not provide as clear feedback on availability. Tools like ping, telnet, or nmap can facilitate these checks.