Quick Definition
An unencrypted remote management protocol that should be replaced by SSH.
Telnet is a legacy remote management protocol that uses TCP port 23. It provides remote CLI access to network devices but transmits all data — including usernames and passwords — in plaintext. Telnet is deprecated for production use; SSH should always be used instead. In lab environments, Telnet may be used for testing TCP connectivity to specific ports.
On the CCNA exam, if a question asks which protocol is more secure for remote management, the answer is SSH (not Telnet). Telnet = unencrypted, SSH = encrypted.
Telnet is a legacy remote management protocol that uses TCP port 23. It provides remote CLI access to network devices but transmits all data — including usernames and passwords — in plaintext. Telnet is deprecated for production use; SSH should always be used instead. In lab environments, Telnet may be used for testing TCP connectivity to specific ports.
On the CCNA exam, if a question asks which protocol is more secure for remote management, the answer is SSH (not Telnet). Telnet = unencrypted, SSH = encrypted.
Telnet falls under the Security domain of the 200-301 exam. Understanding it in context with related terms like ssh and aaa is essential for answering scenario-based questions correctly.