Which of the following is not a common device deployed on a data communication network?

Switch (A): A network switch is a fundamental device used to connect devices in a local area network (LAN) and forward packets based on MAC addresses.

Firewall (B): A firewall is used to filter and protect the network from unauthorized access and threats.

Router (D): A router is essential for forwarding packets between different networks and managing routing.

Agile Controller (C): This is a network automation and management tool rather than a fundamental networking device. Since it is not typically deployed as a core network device, option C is the correct answer.