Networking General

Question 1

Types of virtual circuits

Answer 1

Permanent (PVC): always available and waiting for traffic.

Switched (SVC): Is turned up as needed when traffic needs to pass.

Question 2

Data types at the different OSI layers

Answer 2

Layers 7-5: Protocol data Unit (PDU)
Layer 4 (Transport): Datagram (UDP)/Segment (TCP)
Layer 3 (Network): Packet
layer 2 (data link): Frame
Layer 1 (physical): bits

Question 3

OSI Model Layers (7)

Answer 3

Application
Presentation
Session
Transport
Network
Data Link
Physical

Question 4

TCP/IP Model Layers

Answer 4

Application (Application, presentation, Session)
Transport
Internet (Network)
Link (Data Link/Physical)

Question 5

Common VPN Protocols (5)

Answer 5

Operate at layer 2

PPTP: Obsolete. Initial tunnel negotiation is not encrypted.

L2TP: Combination of PPTP and Cisco Layer 2 Forwarding protocol (L2F). doesn’t provide encryption but is often combined with IPSec ESP for payload encryption.

SSH: Encrypted and limited to transport mode

OpenVPN: Based on TLS and uses pre shared passwords or certificates.

IPSec: Security extension of IP4 and integrated into IPv6. used to establish VPN links between internal/external hosts. Often paired with L2TP. Used both public and private key encryption.

Question 6

IPSec Components (4)

Answer 6

AH: Authentication header (integrity and nonrepudiation)
ESP: Encapsulating Security Payload (Payload encryption)
HMAC: Hash-based message authentication code (Integrity)
IPComp: IP payload Compression