How can a server administrator increase the availability of a web server without clustering?

The correct strategy to increase the availability of a web server without using clustering is to configure round robin DNS entries. This method allows multiple IP addresses to be associated with a single domain name. When a client makes a request to the server, the DNS server responds with one of the available IP addresses in a rotating manner, which distributes the incoming traffic across several servers. This not only balances the load but also provides redundancy; if one server goes down, requests can still be served by the remaining servers.

Configuring an active/active service involves having multiple servers actively processing requests simultaneously, which can be complex and often requires clustering to manage the load efficiently. An active/passive service setup typically involves one server actively handling requests while another is on standby, which may not improve availability since the passive server only becomes active when the primary fails. Configuring two servers with the same IP address would lead to networking conflicts, causing connectivity issues rather than enhancing availability.