H12-811_V1.0 Exam Dumps : HCIA-Datacom V1.0 Exam

Detailed Explanation:The protocol number for TCP in the IPv4 header is 6. Since Telnet uses TCP as its transport layer protocol, the protocol field in the IPv4 header will contain the value 6​​.

Restoring factory defaults on an AR2200 router requires both clearing the current configuration and resetting saved configurations. These steps ensure that any custom settings are removed, reverting the router to its original state. Simply restarting or specifying a startup file without clearing configurations would not remove custom settings​.

Analysis of Possible Causes:

Option A: "The administrator account has been disabled" is a possible cause as a disabled account cannot access the system even if Telnet is enabled.

Option B: Incorrect because the Telnet service being disabled would affect all users, not just one administrator.

Option C: "The administrator account has been deleted" is a valid reason as a deleted account cannot log in.

Option D: "The user level of the administrator account has been changed to 0" is correct. User level 0 typically has insufficient privileges for Telnet access​​.