The best task to perform to resolve this issue is B. Remove the entry for portal.comptia.org from the local hosts file. This is because the local hosts file has a wrong entry that maps portal.comptia.org to 10.10.10.55, which is different from the actual IP address of 192.168.1.55 that is returned by the DNS server. This causes a mismatch and prevents the workstation from accessing the website. By removing or correcting the entry in the hosts file, the workstation will use the DNS server to resolve the domain name and access the website successfully.
To remove or edit the entry in the hosts file, you need to have root privileges and use a text editor such as vi or nano. For example, you can run the command:
sudo vi /etc/hosts
and delete or modify the line that says:
10.10.10.55 portal.comptia.org
Then save and exit the file.