Data Comms

Question 1

List 7 layers of OSI model

Answer 1

All People Seem To Need Data Processing

Application
Presentation
Session
Transport
Network
Data link
Physical

Question 2

What are the four types of physical topology?

Answer 2

Bus
Star
Ring
Mesh

Question 3

What are the major internetworking devices? Discribe function and state OSI level

Answer 3

1. Gateways. Transport level. Translate between protocol and data formats, therefore connecting vastly different networks.
2. Routers. Network level. Send data between network segments using IP address.
3. Bridges/Switches. Data link level. Connect multiple network segments.
4. Repeaters. Physical level. Acts as a digital amplifier.

Question 4

Define attenuation

Answer 4

The gradual weakening of a signal as it passes through a medium. Greater distant and higher frequency increase attenuation. Examples are crosstalk and electromagnetic interference (EMI)

Question 5

How does logical differ from physical topology

Answer 5

Physical topology is the network you can see. Logical topology is the network from the viewpoint of the data

Question 6

Compare UTP, STP and Fibre

Answer 6

UTP is cheaper and more flexible but has lower bandwidth and is susceptible to crosstalk and EMI.
Fiber is more expensive and less flexible but no crosstalk and no EMI.
STP bit of both

Question 7

What parameters can a firewall check?

Answer 7

Firewall can check a packets:

Source and destination address
Protocol
Port number

Question 8

Private IP example

Answer 8

10.20.30.40

Question 9

Class A, B and C subnet mask

Answer 9

A: 255.0.0.0
B: 255.255.0.0
C: 255.255.255.0