Which local configuration provides the strongest password authentication on a router?

The correct answer uses secret 9, which indicates a Type 9 password hash. Type 9 passwords use the SHA-512 algorithm, providing the strongest cryptographic hashing available on Cisco IOS for local user authentication. This makes them highly resistant to brute-force and rainbow table attacks compared to weaker hashing methods. Incorrect options: username netadmin secret 5 $1$b1Ju$kZbBS1Pyh4QzwXyZ1kSZ2 uses secret 5, which is an MD5 hash. While stronger than plain text, MD5 is considered less secure than SHA-512. username netadmin secret $1$b1Ju$k406689705QzwXyZ1kSZ2 is missing the type number (e.g., 5 or 9). By default, if no type is specified, Cisco IOS often defaults to Type 5 (MD5) or an even weaker Type 7 (reversible encryption) depending on the IOS version and configuration, making it less secure than Type 9. line Console 0 password $1$b1Ju$ configures a password for the console line, not a local username. Additionally, it uses a Type 1 hash (MD5), which is weaker than Type 9.