Quick Q&A - Computer Networks
Quick Q&A - Computer Networks
A collection of commonly asked networking questions and concise answers.
General Concepts
Q1: Difference between HTTP and HTTPS?
| Protocol | Security |
|---|---|
| HTTP | Data in plain text |
| HTTPS | Data encrypted using SSL/TLS |
Q2: TCP vs UDP?
TCP:
- Reliable
- Slower
- Connection-oriented
- Used in: Web, Emails
UDP:
- Fast
- Not reliable
- Connectionless
- Used in: Gaming, Streaming
Q3: What happens when you type google.com in browser?
- DNS resolves domain to IP
- Browser connects to server (TCP handshake)
- HTTPS handshake (TLS)
- HTTP request sent
- Server responds
- Page loads and renders
Q4: Difference between IP and MAC?
| Type | Description |
|---|---|
| MAC | Physical identifier (hardware) |
| IP | Logical identifier (network) |
Q5: Latency vs Bandwidth?
| Concept | Meaning |
|---|---|
| Latency | Delay in data transfer |
| Bandwidth | Speed/Capacity of connection |
Q6: DNS Caching?
DNS stores resolved results so next time lookup is faster.
Exists at:
- Browser
- OS
- Router
- ISP
Q7: Difference between Router and Switch?
Router:
- Connects different networks
- Works at Network Layer (Layer 3)
- Uses IP addresses
Switch:
- Connects devices in same network
- Works at Data Link Layer (Layer 2)
- Uses MAC addresses
Q8: What is DHCP?
DHCP = Dynamic Host Configuration Protocol
Assigns IP addresses automatically to devices on a network.
Q9: What is ARP?
ARP = Address Resolution Protocol
Maps IP address → MAC address
Q10: What is Packet Loss?
Packets lost during transfer due to:
- Congestion
- Hardware issues
- Weak network signal
Q11: What is Port Forwarding?
Expose internal service to internet via router configuration.
Example: Making a home server accessible from outside.
Q12: VPN in simple words?
Creates secure encrypted tunnel between you and internet.
Q13: Proxy vs VPN?
| Feature | Proxy | VPN |
|---|---|---|
| Hides Identity | Yes | Yes |
| Encrypts Traffic | No | Yes |
Protocol Questions
Q14: What protocol is used for sending emails?
SMTP (Simple Mail Transfer Protocol)
Q15: What protocol is used for receiving emails?
- POP3 (downloads to device)
- IMAP (keeps on server)
Q16: Default port for SSH?
Port 22
Q17: Which protocol keeps mail on server?
IMAP
Q18: FTP vs SFTP?
| Feature | FTP | SFTP |
|---|---|---|
| Encryption | No | Yes |
| Port | 21 | 22 |
| Security | Low | High |
| Protocol Base | FTP | SSH |
Routing Questions
Q19: OSPF vs BGP?
| Feature | OSPF | BGP |
|---|---|---|
| Type | Interior (IGP) | Exterior (EGP) |
| Used In | Inside a network | Between networks |
| Algorithm | Dijkstra | Path Vector |
Q20: What runs the internet?
BGP (Border Gateway Protocol)
Quick Port Reference
| Service | Port |
|---|---|
| HTTP | 80 |
| HTTPS | 443 |
| FTP | 21 |
| SSH | 22 |
| DNS | 53 |
| SMTP | 25 |
| POP3 | 110 |
| IMAP | 143 |
| MySQL | 3306 |
| MongoDB | 27017 |