Which application is used to learn about an operating system’s type and patch level?

A.
Traceroute

B.
Nmap

C.
Whois

D.
Ping

Explanation:
Nmap (“Network Mapper”) is an open source utility for network exploration or security auditing. It was designed to rapidly scan large networks, although it works fine against single hosts. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (ports) they are offering, what operating system (and OS version) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. Nmap runs on most types of computers, and both console and graphical versions are available. Nmap is free software, available with full source code under the terms of the GNU GPL.
One of the features is OS Detection, which involves a feature called TCP/IP Stack Fingerprinting, which is used to determine the OS and the release levels.
Incorrect Answers:
A: Traceroute will not provide information about a system. It is based on an ICMP command and is used to find the route to a target system.
C: Whois is used to determine the primary and secondary name servers and does not expose the OS type or patch level.
D: Ping will not provide information about a system. It is based on an ICMP command and if there is an echo reply, lets you know if the IP address is active.