Final answer:
Troubleshooting steps to find why PC0 can't access www.server.com include checking DNS settings on PC0, verifying serial interfaces and clock rates are correct, and ensuring that routing between HQ and branch is configured properly. The cause could be any of these, but if DNS and serial configurations are fine, then routing could be the main issue.The correct answer is option b. the clock rate on one of the serial links is configured incorrectly.
Step-by-step explanation:
When troubleshooting a network issue where PC0 cannot visit the web server www.server.com, several potential problems should be investigated. One of the first steps in the troubleshooting process is to ensure that the DNS server address configured on PC0 is correct, as it is responsible for resolving domain names into IP addresses. If the DNS server address is incorrect, PC0 will not be able to resolve the domain name of the web server.
Next, we look into the configuration of routers and switches between the PC and the server. Routing configurations, especially the settings that allow the PC to find a path to the server's network, must be correctly set up. If the routing between HQ and the branch is configured incorrectly, packets may not be routed properly and could result in failure to reach the web server. Serial interfaces and clock rates could also be issues. Verify that any serial interface on a branch router and related clock rates are configured correctly to facilitate proper communication between devices.
Ultimately, if you have narrowed down the issues and identified that DNS settings are correct, the serial interfaces and clock rates are set properly, and local networking on PC0 does not have any issues, then routing configurations would be the main suspect. Review routing tables and any static or dynamic routing protocols in place to ensure they properly route traffic from PC0 to www.server.com.