Name two software tools used for OS guessing? (Choose two.

Nmap performs OS detection by sending a series of TCP and UDP probes and analyzing the responses against a database of known OS fingerprints, making it one of the most widely used OS guessing tools.

Snadboy (Revelation) is a password recovery tool that reveals passwords hidden behind asterisks in dialog boxes, not an OS fingerprinting utility.

Queso is a classic OS fingerprinting tool that sends crafted TCP packets and compares the target's TCP/IP stack behavior against a signature database to identify the operating system.

UserInfo is a tool for querying user account information from systems, not for performing OS detection or fingerprinting.

NetBus is a remote access trojan used for unauthorized control of Windows systems, not a tool designed for OS identification.