In order to tailor your tests during a web-application scan, you decide to determine which web- server version is hosting the application. On using the sV flag with Nmap. you obtain the following resp

A WHOIS lookup queries domain registration databases for ownership and contact information, not web server version details returned by a live service.

Banner grabbing is an information-gathering technique where an attacker connects to an open port and reads the service banner returned by the server to determine the software and version. Nmap's -sV (version detection) flag probes open ports and interprets the responses - in this case retrieving 'Apache Server 7.1.6' directly from the HTTP service banner on port 80.

A dictionary attack attempts authentication by systematically trying words from a predefined wordlist, which is not involved in reading service version banners.

Brute forcing systematically tries all possible credential combinations to gain unauthorized access, not to passively identify service versions.