Most Asked Nmap Interview Questions Asked by Big Companies [Updated 2024]

Nmap is the most popular port scanning tool among the cybersecurity community. Nearby each Security Professional used this tool at least once. This tool is a prerequisite for any cyber-security industry especially vulnerability assessments and penetration testing jobs. Another tool Masscan can be used alternative to Nmap.

Here we have discussed the Nmap interview question asked by cybersecurity experts in the interview. Big companies do ask these Nmap questions to check the basic understanding of Nmap. Click Here to know which tool is better - Nmap or Nessus as both are used for vulnerability scanning.

Most Asked Nmap Interview Questions Asked by Big Companies

Q1. Write a ping scan command in Nmap.

Ans: 

$nmap -sn <target>

Q2. Write a Nmap command to scan targets from a file.

Ans:

$nmap -iL <target-file>

<target-file> indicates the list of IP

$cat <target-file> 
   192.168.1.1 
   192.168.1.10-100

Q3. How to write Nmap commands for specific ports and services?

Ans:

$nmap -p80,443 <target> 

#Scan ports 1 to 1000
$nmap -p1-1000 <target> 

#Scan all ports
$nmap -p- <target> 

$nmap -p snmp <target> 

#using wildcard
$nmap -p snmp* <target>

Q4. How to scan a target using default scripts?

Ans:

nmap -sC <target>

-sC option runs default scripts against the target

Q5. How to scan a target using a TCP SYN scan? List out advantages for the same.

Ans:

$nmap -sS -p1-100 <target>

Advantages of TCP SYN scan: fast, hard to detect by the victim

Q6. How can you contribute to the Nmap community?

Ans: You can upload more signatures and fingerprints on URL https://nmap.org/cgi-bin/submit.cgi?

Q7. How to scan a target from a specific interface?

Ans: Although the selection of interface automatically, you can forcefully assign a specific interface also by using the below command.

#nmap -e <interface> <target>

Click here for Nmap cheatsheet

Q8. How to scan a target using a UDP scan? List out advantages for the same.

Ans:

$nmap -sU -sS --host-timeout -p1-100 <target>

--host-timeout option allows skipping slow hosts

Q9. How to write a Nmap script to scan a target for service detection?

Ans:

$ nmap -sV <target>

Q10. How to exclude specific IPs from the range of IP or the whole subnet of IP?

Ans:

$nmap --exclude-file <target-file> 192.168.1.1/16

Q11. Write nmap query for OS detection.

Ans:

$ nmap -O <target>

$nmap -O --osscan-guess <target> 

$nmap -O --osscan-limit <target>

$nmap -O -v <target>

-v option use for verbose mode

--osscan-guess option forces Nmap to guess OS

--osscan-limit option give results for OS if meet by ideal condition

Click here for Information Security Interview Questions

Q12. How to write a Nmap script to scan the target for version detection?

Ans:

$nmap -sV --version-intensity [0-9] <target>

0 indicates low intensity and 9 indicates high intensity.

Q13. Explain the Aggresive Detection command in Nmap.

Ans: Aggresive Detection command enables OS detection (-O), script scanning (-sC), version detection (-sV),  and traceroute (--traceroute)

$nmap -A <target>

Q14.How do you update the Nmap script database on your local computer?

Ans: 

$nmap --script-updatedb

Q15. Write the Nmap script for the ping scan using UDP.

Ans:

$nmap -sn -PU scanme.nmap.org

Q16. How to write a Nmap script to spoof the Mac Address of the attacker?

Ans:

$ nmap -sn -PR --spoof-mac <mac address> <target>

Q17. Write the Nmap command to scan the IPv6 target.

Ans: 

$ nmap -6 -O <target>
$ nmap -6 -sT <target>

Q18. Write a Nmap command to extract whois information.

Ans:

$nmap -sn --script whois-* <target>

Q19. Write a command to print a summary while sending and receiving every packet.

Ans: This command is useful in understanding how Nmap works.

#nmap --packet-trace -n -sn <target>

Q20. List out command options of Nmap for Firewall/IDS Evasion and Spoofing.

Ans:

Nmap options	Description
--ttl <value>	to set IP time-to-live field
-S <target>	spoof source address
-D <decoy1>[,<decoy2>][,ME][,...]	use for an initial host discovery scan
--randomize-hosts	use for randomizing target host order
--spoof-mac <MAC address, prefix, or vendor name>	use for spoof MAC address
--data <hex string>	to append custom binary data to sent packets
--data-length <number>	Append random binary data to sent packets
-f	Use to send tiny fragment packets
--source-port <portnumber> -g <portnumber>	to spoof the source port number
--mtu	for specified maximum transmission unit (MTU)
--proxies <Comma-separated list of proxy URLs>	Use to relay TCP connections through a chain of proxies
--adler32	To use deprecated Adler32 instead of CRC32C for SCTP checksums
--data-string <string>	Use to append a custom string to send packets
--badsum	Send packets with false TCP/UDP checksums

Q21. Is Nmap a vulnerability scanner?

Ans: Nmap is widely used by security analysts as a port scanner. Although, there are many options available to scan basic vulnerabilities by using Nmap.

Q22. Is it illegal to use Nmap?

Ans: Any active scanning security tool must be used by taking written permission from the asset owner. Hence, It is highly recommended to use Nmap by taking appropriate permission from the legitimate owner.

Q23. Is it OK to scan public websites using Nmap like Google, or Yahoo?

Ans: No, any resource must be scanned after taking appropriate approvals in written form. If you participate in the bug bounty of any specific program, it is the responsibility of the bug bounty hunter to read all rules before participation.

Q24. Is Nmap similar to Wireshark?

Ans: Nmap is basically a port scanner that identifies open ports. While Wireshark is a protocol analyzer that helps security engineers to read the structure of different packets.

Q25. Is it possible to scan the IPs of the internal network?

Ans: Nmap tool can scan any IP which is available via the network. Internal IP or private IP may be scanned by connecting the network via VPN or physically connecting the network.