A firewall separates a management workstation from a router. What traffic must the firewall allow for managing the router using telnet?

The correct answer is based on the fact that Telnet, which is a protocol used for remote command-line administration of network devices, operates on port 23 by default. For managing a router through Telnet, the firewall must allow traffic specifically on this port so that commands and data can be transmitted between the management workstation and the router.

To provide a clearer understanding, other options represent different protocols that serve distinct purposes. Port 22 is used for SSH (Secure Shell), which provides a secure method for remote management. Port 80 is associated with HTTP, which is used for accessing web pages, and port 443 is used for HTTPS, which is a secure version of HTTP. Since the context specifically involves managing the router with Telnet, it is crucial that the firewall permits traffic on port 23 to facilitate this interaction successfully.