Technical - Networking

Question 1

TCP vs UDP (Provide examples)

Answer 1

TCP (Transmission Control Protocol):
Purpose: Reliable, ordered, error-checked delivery
How: 3-way handshake(SYN, SYN-ACK, ACK), sequencing, ACKs/timeouts, error checking/checksums.
Examples: HTTP, FTP

UDP (User Datagram Protocol):
Purpose: Fast, connectionless, no delivery guarantees
No Handshake: Fire-and-forget
Examples: DNS, Streaming

Question 2

HTTP/HTTPS

Answer 2

HTTP (Hypertext Transfer Protocol):
Purpose: Transfer web content
Port: 80
Transport: TCP, plain text

HTTPS (HTTP Secure):
Purpose: Secure web content with encryption
Port: 443
Encryption: TLS/SSL (Asymmetric for key exchange, Symmetric for data)

Question 3

TLS vs SSL

Answer 3

SSL (Secure Sockets Layer):
Purpose: Outdated encryption protocol, vulnerable

TLS (Transport Layer Security):
Purpose: Modern, secure encryption
Key Exchange: Asymmetric (RSA/ECDHE), Data Encryption (Symmetric AES)

Question 4

VPN

Answer 4

VPN (Virtual Private Network):
Purpose: Secure, encrypted private network over the internet
Encryption: Encrypts entire packet (payload + headers)
Protocols: IPsec, OpenVPN

Question 5

DNS

Answer 5

DNS (Domain Name System):
Purpose: Translate domain names to IP addresses
Resolution:
Process: Resolver > Root DNS > TLD DNS > Authoritative DNS
Record Types: A (IPv4), AAAA (IPv6), CNAME, MX
Port: 53 (UDP/TCP)

Question 6

DHCP

Answer 6

DHCP (Dynamic Host Configuration Protocol):
Purpose: Automatically assigns IP addresses and network configurations
Process: Discover > Offer > Request > ACK

Question 7

ARP

Answer 7

ARP (Address Resolution Protocol):
Purpose: Resolve IP addresses to MAC addresses
Process: ARP Request > ARP Reply
Cache: Stores IP-MAC mappings

Question 8

Trace egress request from local machine to the internet (Local Machine > OSI > Router/Modem > ISP)

Answer 8

1. Local Machine: Application generates data.
2. OSI Layers: Translated into TCP/UDP segments, packets, and eventually transmitted as frames.
3. Router:
   - NAT: Translates source IP/Port (Ephemeral)
   - Forwards based on routing table
4. Modem: Converts and sends packet to ISP.
5. ISP: Routes packet through its network to destination.

Question 9

Trace ingress response from internet to local machine (ISP > Modem > Router > OSI > Local Machine)

Answer 9

1. ISP: Receives and routes packet to public IP.
2. Modem: Converts and sends packet to router.
3. Router:
   - Reverse NAT: Translates destination IP/Port (Ephemeral)
   - Forwards to machine private IP
4. OSI Layers: Translated from frames into packets and eventually TCP/UDP segments.
5. Local Machine: Application processes received data.

Question 10

OSI vs TCP/IP (Explain layers)

Answer 10

OSI (Open Systems Interconnection):
Purpose: Conceptual model for network protocols
7 Layers: Physical, Data Link, Network, Transport, Session, Presentation, Application

TCP/IP (Transmission Control Protocol/Internet Protocol):
Purpose: Practical framework for network communication
4 Layers: Link, Internet, Transport, Application

Question 11

CIDR vs Subnet Mask (Explain /24 and 255.255.255.0)

Answer 11

CIDR (Classless Inter-Domain Routing):
Purpose: Represent range of IP address
/24: First 24 bits (3 octets) reserved

Subnet Mask:
Purpose: Represent range of IP address
255.255.255.0: First 24 bits (3 octets) reserved

Question 12

Default Gateway

Answer 12

Default route for traffic from a local network to destinations outside of the network