With the block diagram, explain the various components of a computer system. How do you ensure the security of computer based system with respect to various threats?

A computer system = hardware + software + users + data + procedures working together.

Block diagram:

Input → CPU (ALU + CU + Registers) → Output
          ↕
   Memory (RAM/ROM + SSD/HDD + Cache)

Components: Input (keyboard, scanner), CPU (ALU calculates, CU coordinates, registers hold current values), Memory (RAM working, ROM firmware, SSD/HDD permanent, cache for speed), Output (monitor, printer), plus OS, applications and trained operators.

Securing against threats (threat → safeguard pairs):

1. Malware (virus/ransomware/spyware) → Updated antivirus (signature + behaviour), scan pen-drives, block .exe attachments.
2. Phishing and password theft → Spam filters, verify sender, MFA (password + OTP), never share OTP.
3. Hacking via unpatched software → Timely OS/app patching, firewall + IDS/IPS at border, close unused ports.
4. DoS/DDoS → Rate limiting, load balancer, ISP filtering for public result sites.
5. Insider/USB theft and deletion → Role-based access (enter vs approve), logs, USB policy, Recycle Bin + offline full/incremental backup.
6. Eavesdropping → HTTPS, hashed passwords, encrypted Wi-Fi (WPA2+), digital signature for official docs (ETA 2063).

Close: layered people + technology + policy defence; backup tested by restore drill.