N10-009 Question 65
Single answerHTTP: 80A help desk technician reports that users on the internal network cannot load the company intranet site by entering http://intranet.company.local in a web browser. Users receive a timeout error. The web server is online, users can successfully ping the server by name, and HTTPS access to other sites works normally. A network administrator wants to restore access to this specific site with the least disruption to other services. Which action is the best next step?
- A
Verify that TCP port 80 is listening on the intranet web server and allowed through any host or network firewall
- B
Open UDP port 80 on the edge firewall so browsers can reach the intranet site
- C
Change the intranet site to use TCP port 443 because HTTP cannot operate on port 80
- D
Disable DNS on the client systems and connect directly by IP address instead
Show answer and explanation
Correct answer: A
Explanation
This scenario tests practical troubleshooting of an HTTP service. By default, HTTP traffic uses TCP port 80, while HTTPS uses TCP port 443. Because users can ping the server by name, basic DNS resolution and IP connectivity are likely functioning. The timeout when accessing http://intranet.company.local suggests the problem is more likely with the application service or filtering of TCP 80 than with DNS. Best practice is to verify the web server process is listening on TCP 80 and confirm that host firewalls, network firewalls, or ACLs permit that traffic. This aligns with standard TCP/IP service port usage as documented by IANA service name and port number assignments and with common network troubleshooting methodology: verify name resolution, connectivity, service availability, and filtering in a logical order.
- A. Correct.
This is correct. Standard HTTP uses TCP port 80. Since name resolution is already working because users can ping the server by name, the next logical step is to confirm that the web service is actually listening on TCP 80 and that no host-based firewall or network ACL is blocking that port. This directly addresses the symptom while minimizing impact on unrelated services.
- B. Incorrect.
This is incorrect. HTTP uses TCP, not UDP, on port 80. Opening UDP 80 would not restore normal web access to an HTTP service. This distractor targets the common misconception that applications use both TCP and UDP on the same port by default.
- C. Incorrect.
This is incorrect. HTTPS commonly uses TCP port 443, but HTTP absolutely does operate on TCP port 80. Moving the site to 443 would require server reconfiguration and likely certificate deployment, making it more disruptive than necessary. It also does not explain why the existing HTTP service is timing out.
- D. Incorrect.
This is incorrect. DNS does not appear to be the problem because the server responds to ping by name, indicating successful hostname resolution. Disabling DNS would not fix a blocked or unavailable HTTP service and would create additional connectivity issues for users.