Introduction to networks

Question 1

Earliest communication networks relied on circuit switching technology. What technology enabled the evolution of internet and what were the networking devices called?

Answer 1

Packet switching technology and Interface Message Processors (IMP)

Question 2

What was the first network using packet switching technology called?

Answer 2

ARPANET (Advanced Research Project Agency NETwork). It was set up in 1969.

Question 3

What is LAN?

Answer 3

Local Area Network. A computer network that usually covers a limited area such as a home or an office.

Question 4

What are a hub and a repeater?

Answer 4

Repeater is a networking device that connects different devices together. It’s purpose is to regenerate Ethernet signal. (Signal gets weaker over longer distances). Hub is a multiport repeater that can connect to multiple devices.

Question 5

What is a switch?

Answer 5

Switch is an intermediate networking device that uses the data link layer. Switch transfers Ethernet frames to different machines. The destination is determined from a destination MAC address in Ethernet frame’s header.

Question 6

What is a router?

Answer 6

Router forwards IP packets based on the IP-address in the header of the packet. Routers operate on the network layer.

Question 7

What are the three levels in (some) IoT Architecture models?

Answer 7

Sensors/Actuators, edge computing, cloud computing

Question 8

What are sensors and actuators?

Answer 8

Sensors are for detecting and measuring physical world, while actuators do something in the physical world. Example of both could be thermometers and electric motors.

Question 9

What are the different layers in OSI model called, from layer 1 up?

Answer 9

Physical layer, data link layer, network layer, transport layer, session layer, presentation layer, application layer.

Question 10

Describe bus, ring, star and extended star network topologies.

Answer 10

Bus connects all devices on the single cable or structure. In ring topology, devices are connected to exactly two other devices creating a ring. Star uses a central communication device such as an Ethernet switch that all other devices connect to. Extended star is interconnected multiple star topologies.

Question 11

What are the benefits on using extended star topology?

Answer 11

It provides a hierarchical system that is not as vulnerable for failure. It also makes it possible to build larger and more scalable networks.