Networking Interview Questions

What is the OSI model? Explain all 7 layers briefly.

What is the difference between TCP and UDP?

What is DNS and how does DNS resolution work?

What is the difference between HTTP and HTTPS?

What is an IP address? Explain IPv4 vs IPv6.

What is subnetting? How do you calculate the number of hosts in a subnet?

What are ports and what are some well-known port numbers?

What is DHCP and how does it work?

What is NAT (Network Address Translation) and why is it used?

What are ping and traceroute? How do you use them for troubleshooting?

What is a MAC address and what role does it play in networking?

What is ARP and how does it work?

What is a default gateway and why is it important?

What is a firewall and how do firewalls work in Linux?

What is CIDR notation and how do you read it?

What is the difference between L4 and L7 load balancing?

What is a reverse proxy and how is it different from a forward proxy?

Explain the TCP 3-way handshake and 4-way teardown.

What are the different DNS record types? When do you use each?

What is a VPN and what are the different types?

Explain SSL/TLS in detail. How does the TLS handshake work?

What is a CDN and how does it improve performance?

What network troubleshooting tools should every DevOps engineer know?

What is MTU and how can MTU issues cause network problems?

What is a VLAN and how does it work?

How do iptables rules work? Walk through the chain processing order.

What are routing protocols? Explain static vs dynamic routing.

How does HTTP/2 differ from HTTP/1.1 and what is HTTP/3?

What is the difference between a stateful and stateless firewall?

Explain how Docker networking works. What are the different network drivers?

What is BGP and why is it important for cloud and DevOps?

How does Kubernetes networking work? Explain the networking model and CNI.

Explain Kubernetes Service types: ClusterIP, NodePort, LoadBalancer, and ExternalName.

What are Kubernetes NetworkPolicies? How do you implement them?

What is a service mesh? How does Istio/Linkerd handle networking?

What is eBPF and how is it revolutionizing networking in DevOps?

What is cloud VPC Peering and Transit Gateway? When do you use each?

What is zero trust networking and how do you implement it?

What is mTLS (Mutual TLS) and how does it differ from regular TLS?

How does DNS-based service discovery work in Kubernetes and beyond?

What is kube-proxy and what are its different modes?

What are Linux network namespaces and how do containers use them?

How does IPv6 work in production DevOps environments?

What is DPDK and when would a DevOps engineer encounter it?

How does DDoS mitigation work at the network level?

What is SPIFFE/SPIRE and how does it enable workload identity?

How do you troubleshoot a Kubernetes Pod that cannot reach an external service?

What is the difference between ingress and egress traffic? How do you control each in Kubernetes?

What is network observability and how do you implement it in a cloud-native environment?

Explain Kubernetes Gateway API and how it improves on Ingress.