A network is a group of interconnected devices that communicate to share resources and information. It can be wired or wireless.

Model OSI

Application OSI Model TCP/IP Model DNS, P2P, SMTP, FTP Presentation HTML, DOC, JPEG, MP3 Session Session establishment in TCP, SIP, RTP Network IP, ARP, IPSec, ICMP Data Link MAC, Ethernet, 802.11, VLAN Physical RS-232, RJ45, SDH, DSL Transport 1 2 3 4 1 2 3 4 5 6 TCP, UDP, SSL, TLS Internet IP, ARP, IPSec, ICMP Network Access Ethernet, Token Ring, PPP, Frame Relay Transport TCP, UDP, SSL, TLS Application HTTP, RDP, DNS, SMTP 7
  1. Physical (RS-232, RJ45, 802.11): Physical connection between devices, including cables and switches.
  2. Data Link (): Facilitates data transfer between devices on the same network, managing error control and flow control.
  3. Network (): Responsible for data routing and forwarding across different networks.
  4. Transport (): Ensures complete data transfer and error recovery between end systems.
  5. Session (): Manages sessions between applications, establishing, maintaining, and terminating connections.
  6. Presentation (): Translates data formats, encrypts, and compresses data for the application layer.
  7. Application (): Interfaces directly with end-user applications, providing services like email and file transfer.

TCP/IP

TCP/UDP

HTTP

DNS

Interview Questions

  1. What is a network ?
  2. What is an IP address ?
  3. What is the difference between IPv4 and IPv6 ?
  4. What are private and public IP addresses ?
  5. What is a subnet mask ?
  6. What is DHCP , and how does it work?
  7. What is DNS , and why is it important?
  8. What is NAT ?
  9. What is a firewall ?
  10. What are the types of firewalls ?
  11. What is a VPN ?
  12. What is SSH , and why is it used?
  13. What is HTTP and HTTPS ?
  14. What is an SSL/TLS certificate ?
  15. What is a load balancer?
  16. What are different types of load balancers?
  17. What is a DMZ in networking ?
  18. What is port forwarding?
  19. What is ARP (Address Resolution Protocol)?
  20. What is an IDS and IPS?
  21. What is Zero Trust Security?
  22. What is the difference between symmetric and asymmetric encryption?
  23. What is a CDN (Content Delivery Network)?
  24. What is the difference between TCP and UDP?
  25. How does a reverse proxy improve security?
  26. What are the benefits of HTTPS over HTTP?
  27. How does multi-factor authentication (MFA) enhance security?
  28. What is a bastion host?
  29. What is OSI Model and its layers?
  30. What is a WAF (Web Application Firewall)?
  31. What is a honeypot in cybersecurity?
  32. What is BGP (Border Gateway Protocol)?
  33. What is DDoS, and how can it be mitigated?
  34. What is the CIA Triad in security?
  35. What is SSO (Single Sign-On)?
  36. What is a security token?
  37. What is an access control list (ACL)?
  38. What is a container network security concern?
  39. What is network segmentation?
  40. What is the difference between active and passive reconnaissance?
  41. What is mutual TLS (mTLS), and why is it used?
  42. What is the difference between L3, L4, and L7 firewalls?
  43. How does AWS Security Groups differ from Network ACLs?
  44. What is a SIEM (Security Information and Event Management) system?
  45. What is a threat model in security?
  46. What is an ephemeral port, and how is it used?
  47. How does DNSSEC enhance DNS security?
  48. What are the different types of VPNs?
  49. How does a service mesh improve security in Kubernetes?
  50. What are some common OWASP Top 10 security risks?
  51. How do WebSockets handle security concerns?
  52. What is an SSRF (Server-Side Request Forgery) attack?
  53. How does an AWS WAF protect applications?
  54. How does Kubernetes RBAC (Role-Based Access Control) work?
  55. What is a MAC address, and how does MAC filtering enhance security?
  56. How does DNS poisoning work, and how can it be prevented?
  57. What is a federated identity in security?
  58. How does Kubernetes Network Policy improve security?
  59. What is the principle of least privilege (PoLP)?
  60. How do HSTS (HTTP Strict Transport Security) and CSP (Content Security Policy) improve web security?