Answer:
"nslookup" is the best troubleshooting tool to use in this situation to figure out where the problem is.
Nslookup is a command-line tool that can be used to ask DNS (Domain Name System) servers for information about how a domain name maps to an IP address. In this case, the administrator can ping a web server using its IP address, but he or she can't go to the website's domain name. This means that there might be a problem with the way DNS resolves that domain name.
The administrator can use nslookup to ask the DNS server if the domain name resolves to the right IP address. If the domain name doesn't resolve right, it could mean that there is a problem with the DNS server or with the DNS records for the domain name.
So, nslookup can help the administrator figure out if the problem is related to DNS or not. If it is, it can help narrow down the problem if it is related to DNS.