CompTIA Network+ (N10-006) — Question 48

An administrator's network has OSPF for the internal routing protocol and has two interfaces that continue to flap. The administrator reviews the following output:
Fast ethernet 0 is up, line protocol is up
Int ip address is 10.20.130.5/25
MTU 1500 bytes, BW10000 kbit, DLY 100 usec
Reliability 255/255, Tx load 1/255, Rx load 1/255
Encapsulation ospf, loopback not set

Keep alive 10 -
Full duplex, 100Mb/s, 100Base Tx/Fx

Received 1052993 broadcasts -
1258 input errors
983881 packet output, 768588 bytes
1747 output errors, 0 collisions, 423 resets
Which of the following problems would cause the interface flap?

Answer options

• A. Wrong IP address
• B. Loopback not set
• C. Bad wire
• D. Incorrect encapsulation
• E. Duplex mismatch

Correct answer: E

Explanation

The correct answer is E, as a duplex mismatch can cause significant communication issues, leading to interface flapping. Options A, B, C, and D are less likely to cause the described symptoms since the IP address appears correct, the loopback setting does not directly affect interface status, while a bad wire or incorrect encapsulation would typically cause connectivity issues rather than flapping.