3.3 Network Charcteristics

Question 1

What is a computer network

Answer 1

A computer network is a collection of computers linked together so that they can communicate with each other.

Question 2

Peer to peer network - used for small offices/home networks

Answer 2

Two or more Pc’s share files and access devices such as printers without requiring a central server.

Access rights are controlled by setting sharing permissions on individual machines Access rights are controlled by setting sharing permissions on individual machines

each Computer functions both as a client and as a server simultaneously

􏰀 Each computer must be backed up.

􏰀 Data can be deleted by users

􏰀 If some PC’s on the network are slow they will slow down other machines.

Question 3

Client server characteristics - used for business requiring control and security of information

Answer 3

End Users (clients) can access resources from a central computer called the server.
􏰀 Clients are dependent on the server working properly .
􏰀 Servers manage the system sending programs and data to the client machines

Servers can be updated to improve performance

􏰀 Security is centrally controlled keeping the system more secure.

The server controls security, contains a list of usernames and passwords. Once logged on, users may access only those resources that the network administrator allows them to access.

Users require logins to access the network.

􏰀 All data is backed up centrally on the main server

Question 4

Peer to peer advantages

Answer 4

Cost saving – No server is needed

Lower operating costs

Status – All machines have same equal status

No network manager is needed

Easy to set up

No reliance on a server

Peer responsibility

Question 5

Peer to peer disadvantages

Answer 5

Backups cannot be made centrally

Security There’s no central security or any way to control who shares what

Harder to find files which are not stored centrally

Network size - Only suitable for very small networks

Question 6

Client server advantages

Answer 6

Users need little specialist knowledge as administration is performed centrally

Security is better as it is centralised and one person’s

Backups and software installation can be done centrally.
Centrally stored files are easier to find.
More efficient / load tolerant for large networks.

Question 7

Client server disadvantages

Answer 7

More expensive

Cost of setup and maintenance is higher.

One machine more important than the rest, dominates the network, overreliance.

Need specialist knowledge

Network manager allocates access to resources on the network.

Network operating systems require technical knowledge to set up and maintain.

If server breaks down network is unusable.

Question 8

What is an IP address

Answer 8

unique address that identifies a host on a network

Question 9

What is a URL

Answer 9

URL - unique identifier used to locate a web page/resource on the Internet. We can remember a URL,

Question 10

DNS server

Answer 10

The DNS Server resolves or translates those domain names to IP addresses as requested.

􏰀 A DNS server is a computer server that contains a database of public IP addresses and their associated hostnames. A hostname is a domain name assigned to a host computer

Question 11

What a a topology

Answer 11

A topology refers to the physical layout of a network.

Question 12

Bus networks - used for small networks

Answer 12

Each computer and network device is connected to a single cable called the backbone

Depending on the network card each computer can be connected via a coaxical cable or RJ 45
Terminators required at each end of the cable,

Bus network will usually use the carrier sense multiple (CSMA) access network

already data being transmitted the computer has to try again

two or more computers will start transmitting at the same time, a collision will occur which
will be detected by the computers that are transmitting, they will stop and try again later.

Collisions result in a voltage displacement on the cable. This makes it possible for the stations to detect
the collisions

Question 13

Bus network advantages

Answer 13

Attaching a new device is easy,

It is cheaper in cabling terms than a star network

• Transmissions are in both directions

Transmission is more likely to be read

Question 14

Bus network disadvantages

Answer 14

• Hard to troubleshoot

Damaged cable results in network failure

• Adding additional devices can slow the network down significantly the possibility of the
transmissions crashing into each other.

Not used for large networks.

Question 15

Star network - most common setup used in homes and offices

Answer 15

All the computers communicate through the central hub, switch or computer

This switch, hub or Computer will act as a server and other computers clients

Depending each computer can be connected via a cable e,g Ethernet and use RJ45 Connector

Question 16

Star network advantages

Answer 16

More fault tolerant if a spoke fails the others still work.

▸ Adding (Load Tolerant) or removing network nodes
is easy, and can be done without affecting the network.

Due to the centralised nature, it is easy to detect faults in the network devices.

Question 17

Star network disadvantages

Answer 17

Network operation depends on the functioning of the central hub. Hence, central hub failure leads to failure of the entire network.

The number of nodes that can be added and performance, depends on the capacity of the central hub.

The setup cost is quite high

Question 18

Ring network - rarely used now, but was in school and small offices

Answer 18

Use a method known as token passing to prevent problems of multiple messages on the network colliding

Device connections tend to be in a circular path, Rings (does not always have a ring shape,
see image)

A small data packet known as the token, the token travels around a logical “ring” of workstations or servers is continuously transmitted around the ring in one direction.

A token is a unique series of bits that travel around a token ring network. As the token circulates, computers linked to the network can seize it

Question 19

Ring network advantages

Answer 19

The data being transmitted between two nodes passes through all the intermediate nodes. A central server is not required for the management of this topology.It is less costly than a star topology as less cabling/no server.

The traffic is one direction and the data transmission is high-speed

Reduced packet collision as each node releases a data packet after receiving the token

● Performs well under heavy traffic compared to bus network

The adding or removing of network nodes is easy,

Question 20

Ring network disadvantages

Answer 20

The failure of a single node in the network can cause the entire network to fail

▸ The movement or changes made to network nodes affects the entire network’s performance

▸ Data sent from one node to another has to pass through all the intermediate nodes. This makes the transmission slower in comparison to that in a star topology

▸ There is heavy dependency on the wire connecting the network nodes in the ring

Question 21

Mesh network

Answer 21

Every node [connection] in the network is connected directly to most other nodes. If a connection stops working all the traffic on the network can be rerouted around the problem.

Each connection can carry its own data load, making it a very robust network.

Provides greater security and privacy

The internet is the best example

Used for wireless networking as it’s quick and easy to setup

Used where locations don’t have an Ethernet connection e.g. outdoor concert
venues, warehouses, transportation

Question 22

Mesh network advantages

Answer 22

All nodes/devices are separately connected to all other nodes , arrangement of the network
nodes is such that it is possible to transmit data from one node to many other nodes at the same
time.

● If one node breaks rest of system can continue as if nothing has happened. The failure of a
single node does not cause the entire network to fail as there are alternate paths for data transmission. Network can “self heal” if there is a breakdown, so no service interruption.
It can handle heavy traffic,

easy to identify/diagnose fault

Question 23

Mesh network disadvantages

Answer 23

many connections serve no major purpose. This leads to redundancy of many network

▸ A lot of cabling is required.

Installation and configuration can be difficult

Question 24

What is a subnet mask

Answer 24

A number that defines the range of IP addresses that can be used in a network.

Question 25

What is a default gateway

Answer 25

A default gateway is an access point or IP router used to send information from a computer on one network to a computer on another network or the internet.

Question 26

IP addresses

Answer 26

􏰀 It identifies a host on a network

􏰀 A unique address that different computers on a network use to identify
and communicate with each other; each device on a network must
have it’s own unique IP address.

Private IP Address and Public IP Address are used to uniquely identify a machine on the internet.

Private up adress used local network

Question 27

What is subnet mask used for

Answer 27

The subnet mask is used to subdivide a network into smaller, more manageable chunks. In order for a sending device to transmit data to a receiving device, the sender needs to know where the destination is. The destination will either be on the same subnetwork as the source, or on some other subnetwork