CompTIA Network+ N10-007 Exam: Troubleshooting 169.254.x.x IP Address Issues

Ports to Check on Local Server Firewall: 67 and 68

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Question

A technician notices clients are receiving a 169.254.x.x IP address following the upgrade of a server.

Which of the following ports should the technician check on the local server firewall?

A.

ports 20 and 21 B.

ports 67 and 68 C.

ports 80 and 443 D.

port 123 and 8080

B.

Explanations

A technician notices clients are receiving a 169.254.x.x IP address following the upgrade of a server.

Which of the following ports should the technician check on the local server firewall?

A.

ports 20 and 21

B.

ports 67 and 68

C.

ports 80 and 443

D.

port 123 and 8080

B.

When clients receive a 169.254.x.x IP address, it means they have failed to obtain an IP address from a DHCP server. The IP address 169.254.x.x is known as Automatic Private IP Addressing (APIPA) and is assigned to a device when it cannot find a DHCP server on the network.

To resolve this issue, the technician should check the DHCP server's settings and ensure that it is properly configured to assign IP addresses to clients. However, if the clients are still receiving the 169.254.x.x IP address even after checking the DHCP server, the technician should investigate the local server firewall.

The correct answer is B. Ports 67 and 68. These are the ports used by DHCP for communication between the client and the server. If the firewall on the server is blocking these ports, clients will not be able to obtain an IP address from the DHCP server, and will instead receive a 169.254.x.x IP address.

Option A, ports 20 and 21, are used for FTP (File Transfer Protocol) data transfer. Option C, ports 80 and 443, are used for HTTP (Hypertext Transfer Protocol) and HTTPS (HTTP Secure) web traffic. Option D, port 123 and 8080, are used for NTP (Network Time Protocol) and HTTP proxy respectively. None of these ports are directly related to DHCP communication.

In summary, if clients are receiving a 169.254.x.x IP address, the technician should check the DHCP server's settings and investigate the local server firewall to ensure that ports 67 and 68 are not being blocked.