Networking and Engineer Interview Questions and Answer – Part 3

  • What is localhost and why would ping localhost fail?
  • 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?
Rajesh Kumar
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