Final answer:
The server likely to be rebooted for DNS issues is a BIND server, which is DNS software commonly used for resolving domain names to IP addresses. The correct multiple-choice option is (c).
Step-by-step explanation:
If you are asked to reboot your DNS server, you are most likely dealing with a server that handles the resolution of domain names to IP addresses. The likely server in question here would be a C) BIND server. BIND stands for Berkeley Internet Name Domain, which is a commonly used DNS software.
Unix servers can run a variety of services, including DNS, but the type of server is determined by the application it runs, not the operating system. An Apache server refers to a web server software, not DNS, and a Web server generally refers to a server that delivers web pages, also not directly related to serving DNS queries. The correct multiple-choice option is (c).