questions Flashcards
(35 cards)
IP
Logical addressing Network
ICMP
Diagnostics (ping, traceroute)
Network
TCP
Reliable communication Transport
UDP
Unreliable communication Transport
ARP
Resolves IP to MAC addresses Layer 2/3
DNS
Resolves domain names to IPs Application
DHCP
Assigns IP addresses dynamically
Application
Diagnostic Tools in OSI
ping – Checks connectivity using ICMP Echo Request
tracert (Windows) / traceroute (Linux) – Traces path packets take
ipconfig / ifconfig – Displays IP configuration
nslookup – Queries DNS servers
Important Terms in OSI
Segmentation
Encapsulation
TTL (Time to Live)
ACK
SYN
Segmentation: Breaking large messages into smaller segments (Transport layer)
Encapsulation: Wrapping data with protocol-specific headers
TTL (Time to Live): Limits the lifespan of a packet
ACK: Acknowledgment in TCP
SYN: Synchronize sequence numbers
. Port Numbers
HTTP
HTTPS
FTP:
DNS
DHCP
SSH
HTTP: 80
HTTPS: 443
FTP: 21
DNS: 53
DHCP: 67/68
SSH: 22
Three-Way Handshake (TCP)
SYN – Client sends a synchronization request
SYN-ACK – Server acknowledges and replies
ACK – Client acknowledges
Summary of the TCP Three-Way Handshake:
Step Who sends it Meaning
1 Client → Server SYN: Request to start connection
2 Server → Client SYN-ACK: Acknowledge and synchronize
3 Client → Server ACK: Acknowledge server’s reply, connection established
Q: How many layers are in the OSI model?
7 layers
Q: What is a common mnemonic to remember the OSI layers (top-down)?
All People Seem To Need Data Processing
(Application, Presentation, Session, Transport, Network, Data Link, Physical)
Top-Down: All People Seem To Need Data Processing
Bottom-Up: Please Do Not Throw Sausage Pizza Away
Q: What is the function of the Application layer?
A: Interface between user applications and the network (e.g., HTTP, FTP, SMTP)
Q: Give 2 protocols that operate at the Application layer.
A: HTTP, SMTP
Q: What does the Presentation layer do?
A: Translates, encrypts, and compresses data
Q: What formats are handled in presentation lazer?
A: JPEG, MPEG, SSL/TLS encryption
Q: What is the role of the Session layer?
A: Manages sessions/connections between applications
Q: What does the Session layer establish, manage, and terminate?
A: Communication sessions
Q: What does the Transport layer ensure?
A: Reliable delivery (or fast delivery) of data
Q: What does the Transport layer ensure?
A: Reliable delivery (or fast delivery) of data
Q: What are the two main protocols in transport layer?
A: TCP (reliable), UDP (unreliable)
Q: What identifiers are used in transprot layer?
A: Port numbers
Q: What is the primary function of the Network layer?
A: Routing and logical addressing (IP)
