- What is localhost and why would
ping localhostfail? - What is the similarity between “ping” & “traceroute” ? How is traceroute able to find the hops.
- What is the command used to show all open ports and/or socket connections on a machine?
- Is 300.168.0.123 a valid IPv4 address?
- Which IP ranges/subnets are “private” or “non-routable” (RFC 1918)?
- What is a VLAN?
- What is ARP and what is it used for?
- What is the difference between TCP and UDP?
- What is the purpose of a default gateway?
- What is command used to show the routing table on a Linux box?
- A TCP connection on a network can be uniquely defined by 4 things. What are those things?
- When a client running a web browser connects to a web server, what is the source port and what is the destination port of the connection?
- How do you add an IPv6 address to a specific interface?
- You have added an IPv4 and IPv6 address to interface eth0. A ping to the v4 address is working but a ping to the v6 address gives you the response
sendmsg: operation not permitted. What could be wrong? - What is SNAT and when should it be used?
- Explain how could you ssh login into a Linux system that DROPs all new incoming packets using a SSH tunnel.
- How do you stop a DDoS attack?
- How can you see content of an ip packet?
- What is IPoAC (RFC 1149)?
- What will happen when you bind port 0?
I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.
I publish technical articles at DevOps School, travel stories at Holiday Landmark, stock market insights at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow, and SEO and digital marketing strategies at Wizbrand.
Find Trusted Cardiac Hospitals
Compare heart hospitals by city and services — all in one place.
Explore Hospitals