1️⃣
Introduction to Networking
- What is a computer network?
- Types of Networks: LAN, MAN, WAN, PAN
- Network Topologies: Bus, Star, Ring, Mesh, Hybrid
- Transmission Modes: Simplex, Half Duplex, Full Duplex
- Bandwidth vs Throughput vs Latency
- OSI Model vs TCP/IP Model (basic overview)
2️⃣
OSI Model (7 Layers)
- Physical Layer – Cables, Signals, Data Rates
- Data Link Layer – MAC Address, Ethernet, ARP
- Network Layer – IP Address, Routing, Packets
- Transport Layer – TCP/UDP, Ports, Handshake
- Session Layer – Session management
- Presentation Layer – Data formats, Encryption
- Application Layer – HTTP, FTP, DNS
Focus for Interviews:
- Diagram of OSI model
- OSI vs TCP/IP comparison
- Functions of each layer with examples
3️⃣
IP Addressing & Subnetting
- IPv4 and IPv6 basics
- IP Classes (A to E)
- Subnetting with practice (CIDR Notation)
- Subnet mask and Network ID calculation
- Public vs Private IPs
- Binary IP to decimal conversion
4️⃣
TCP vs UDP + Transport Layer
- TCP: Reliable, Ordered, Connection-oriented
- UDP: Fast, Unreliable, Connectionless
- TCP Header + Flags (SYN, ACK, FIN)
- 3-Way Handshake and 4-Way Termination
- Flow Control and Congestion Control
- Port Numbers
5️⃣
Routing & Switching
- Router vs Switch vs Hub vs Bridge
- Routing Protocols: RIP, OSPF, BGP
- Routing Algorithms: Dijkstra, Bellman-Ford
- MAC Address Table, ARP protocol
- Default Gateway, NAT
6️⃣
Application Layer Protocols
- HTTP vs HTTPS
- HTTP Methods: GET, POST, PUT, DELETE
- HTTP Status Codes: 200, 404, 500, etc.
- FTP – File Transfer
- DNS – Name Resolution process
- DHCP – Assigning IP dynamically
- SMTP/POP3/IMAP – Mail protocols
7️⃣
Network Devices
- Modem, Router, Switch, Hub
- Bridge, Repeater, Gateway
- Firewall: Stateless vs Stateful
- Load Balancer
8️⃣
Network Security Basics
- HTTPS (with TLS/SSL)
- Public Key vs Private Key (RSA, AES)
- Types of Attacks: DoS, DDoS, MITM, Phishing
- VPN (Virtual Private Network)
- Firewalls: Rules, Packet Filtering
9️⃣
Debugging Tools
- ping – Check connectivity
- traceroute – See path to server
- nslookup, dig – DNS details
- netstat – List open ports
- ipconfig / ifconfig
- Wireshark – Packet analysis
🔟
Modern Concepts
- NAT – Network Address Translation
- Proxy vs Reverse Proxy
- CDN – Content Delivery Network
- Load Balancer – Round Robin, Least Connections
- SDN – Software Defined Networking
- Cloud Networking: AWS VPC, Subnets
🔐
Network Security & Attacks
- Authentication: Kerberos, LDAP, OAuth
- Encryption: Symmetric vs Asymmetric
- SSL/TLS Handshake process
- Common Attacks: SQL Injection, XSS, CSRF
- Network Attacks: ARP Spoofing, MAC Flooding
- IDS/IPS – Intrusion Detection/Prevention
⚡
Performance & Quality of Service
- QoS (Quality of Service) concepts
- Traffic Shaping vs Traffic Policing
- Congestion Control: AIMD, Slow Start
- Buffer Management: Drop Tail, RED
- Network Metrics: RTT, Jitter, Packet Loss
- SLA – Service Level Agreement
🌊
Error Detection & Correction
- Checksum – Internet Checksum
- CRC (Cyclic Redundancy Check)
- Hamming Code for error correction
- Parity Check – Even/Odd parity
- ARQ Protocols: Stop-and-Wait, Go-Back-N
- Flow Control: Sliding Window Protocol
📡
Wireless Networks & IoT
- WiFi Standards: 802.11 a/b/g/n/ac/ax
- Wireless Security: WEP, WPA, WPA2, WPA3
- Mobile Networks: 3G, 4G LTE, 5G
- Bluetooth and protocol stack
- IoT Protocols: MQTT, CoAP, LoRaWAN
- Mesh Networks and topology
🔄
Advanced Routing Concepts
- VLAN – Virtual Local Area Network
- MPLS – Multi-Protocol Label Switching
- BGP – Border Gateway Protocol details
- OSPF Areas and LSA types
- Route Redistribution
- Policy-Based Routing
☁️
Cloud & Virtualization
- Virtual Networks: VXLAN, GRE Tunnels
- Container Networking: Docker, Kubernetes
- Network Functions Virtualization (NFV)
- Service Mesh: Istio, Linkerd
- API Gateway and microservices
- Edge Computing concepts
🔍
Network Monitoring & Troubleshooting
- SNMP – Simple Network Management Protocol
- Syslog and log analysis
- NetFlow/sFlow for traffic analysis
- Network Topology Discovery
- Performance Monitoring Tools
- Fault Management strategies
📌 High-Frequency Interview Questions
- What happens when you type google.com?
- Explain 3-way TCP handshake.
- Difference between TCP and UDP.
- How does DNS work?
- What is Subnetting?
- What is NAT and how does it help?
- What is a Firewall?
- Explain OSI Model with examples.
- How does HTTPS work? Explain SSL/TLS handshake.
- What is the difference between Hub, Switch, and Router?
- Explain ARP protocol and ARP table.
- What is DHCP? How does it work?
- Difference between IPv4 and IPv6.
- What is VLAN and why is it used?
- Explain different types of network attacks.
- What is load balancing? Types of load balancing.
- How does VPN work?
- What is CDN and how does it improve performance?
- Explain congestion control in TCP.
- What is the difference between symmetric and asymmetric encryption?
🎯 Technical Deep-Dive Questions
- Design a chat application architecture.
- How would you troubleshoot slow network performance?
- Explain BGP path selection algorithm.
- Design a secure network for a company with 1000 employees.
- How does HTTP/2 improve over HTTP/1.1?
- Explain the working of OSPF routing protocol.
- How do you prevent DDoS attacks?
- Design a scalable web architecture.
- Explain network address translation in detail.
- How does Quality of Service (QoS) work?
💡 Scenario-Based Questions
- Network is slow, how do you diagnose the problem?
- Users can't access a specific website, troubleshoot steps?
- How to implement network security for remote work?
- Design network topology for a multi-branch company.
- How to handle network outage during peak hours?
- Implement redundancy in network design.
- Choose appropriate routing protocol for different scenarios.
- Handle IP address exhaustion in your network.