What types of virus scanners exist?
Scanner (conventional scanner, command-line scanner, on-demand scanner) – a program that looks for known viruses by checking for recognisable patterns (‘scan strings’, ‘search strings’, ‘signatures’ [a term best avoided for its ambiguity]). TSR scanner – a TSR (memory-resident program) that checks for viruses while other programs are running. It may have some of the characteristics of a monitor and/or behaviour blocker. VxD scanner – a scanner that works under Windows or perhaps under Win 95, or both), which checks for viruses continuously while you work. Heuristic scanners – scanners that inspect executable files for code using operations that might denote an unknown virus. Monitor/Behaviour Blocker – a TSR that monitors programs while they are running for behaviour which might denote a virus. Change Detectors/Checksummers/Integrity Checkers – programs that keep a database of the characteristics of all executable files on a system and check for changes which might signify an attack by