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

WHOIS lookup queries domain registration databases for ownership and contact records, not live service banners from a running web server.

Banner grabbing is a passive information-gathering technique where an attacker reads the response header or banner a service returns when queried. Nmap's -sV flag sends probe requests to open ports and parses the service banner - in this case extracting 'Apache Server 7.1.6' from the HTTP response - to identify software and version without attempting any credentials or guessing.

A dictionary attack attempts authentication by trying a list of known words or passwords against a login mechanism; no credentials are being tested when running Nmap -sV.

Brute forcing exhaustively tries all possible credential combinations against an authentication service, which is unrelated to reading version banners from open service ports.