1. Level 2 Diploma Unit 10 Setting up an IT Network
Network Addressing

2. OSI Layers 1 to 4 OSI Physical layer 1 OSI Data link layer 2
Network media – the cables/wireless and adapters
OSI Data link layer 2
Method of transferring data between network adapters
Organises data streams into frames
Uses MAC addresses
OSI Network layer 3
Routes packets between networks
Uses IP addresses

3. OSI (Open Systems Interconnect) model
7 layers
Each layer provides a service for the layer above and uses the services of the layer below
Each layer (except the physical) attaches a header
Headers provide control information

4. Frames
Address used is the 48 bit unique MAC (Media Access Control) address hard coded into the adapter

5. Network Layer 3 Data messages are split into smaller packets Routers
Better chance of successful delivery
Easier to resend if lost or damaged
Routers
Choose the path that packets take around the network
Packets are given a time to live (TTL) to prevent them travelling for ever
Internet Protocol (IP) and IP addressing
Provides network identification and addressing
An IP address is a 32 bit binary value expressed as dotted decimal is easier as

6. Restricted addresses Type Range Comment Private–
Class A – –
Class B –
Class C
Loopback –
Tests host function
Multicast –
Broadcast to many hosts
Reserved
Not permitted – – – –

7. I. P Addresses 11000000101010000000000100000101 What is a ’bit’?
www.

8. Network Address Translation
Private networks connect to the Internet via a router
Host’s private address is translated to a valid public address by the router using NAT
Easier IP configuration
Hosts protected from direct internet access
Can map 1:1 or use port addresses to map n:1

9. ARP and ICMP ARP (Address resolution protocol)
Network layer
Converts IP addresses to MAC addresses
Converts MAC addresses to IP addresses
ICMP (Internet control message protocol)
Used for diagnostic and troubleshooting tools
PING
TRACERT

10. TCP and UDP Layer 4 TCP Transmission Control Protocol
Reliable
Connection oriented packet transfer
TCP/IP applications use a unique identification number called a port
An IP address and a port make a socket
Socket to socket connections make a path
where 80 is the port number

11. Common port numbers Port Number Process Name Description 20 FTPDATA
File transfer protocol – Data 21
FTP
File transfer protocol – Control 22
SSH
Secure shell 23
TELNET
Telnet 25
SMTP
Simple Mail Transfer Protocol 53
DNS
Domain Name Service 69
TFTP
Trivial FTP 80
HTTP
Hypertext Transfer Protocol
110
POP3
Post Office Protocol 3
119
NNTP
Network News Transfer Protocol
123
NTP
Network Time Protocol
139
NetBIOS
Session port
143
IMAP4
Internet Mail Access Protocol
389
LDAP
Directory Access Protocol
443
HTTPS
HTTP Secure

12. HTTP and HTML Hypertext transfer protocol
Web browsers request resources from web servers by
connecting to port 80
Using a Uniform Resource Identifier (URI)
Common web servers are
Apache (open source)
Microsoft Internet Information Server (IIS)
HTTP is used to serve HTML (Hypertext MarkUp language) pages which describe how the text should be displayed

13. SSL/TLS HTTP is not encrypted and does not authenticate
SSL (Secure sockets layer) and TLS (Transport Layer Security)
Provide cryptographic security
Used with HTTPS
Uses port 443
Puts in the URI
Adds a padlock icon in the browser

14.
Plain text
File attachments encoded in MIME (multipurpose internet mail extensions)
Send mail out using SMTP
Simple mail transfer protocol
Receive mail using
POP3 or IMAP4
Can be secured using PGP (Pretty Good Privacy or Secure MIME

15. FTP File transfer protocol More efficient then e-mail
Plain text transfer
Most browsers include an FTP client
ftp://ftp.microsoft.com/

16. Instant Messaging
Exchange of text messages with contacts

17. Domain names
Every host on the internet has a unique, 32 bit IP address
For convenience each host also has a Fully Qualified Domain Name (FQDN)
Domain Name Servers cross reference between domain names and IP addresses
An FQDN is hierarchical
www as a local domain indicates the resource is a web server
A Subdomain has to be registered and identifies a company, organisation or individual
Top level domain
local domain
Subdomain

18. Top level domain names Domain Name Description edu
Educational and research institutes
gov
Government agencies
mil
Military institutions
net
Network companies (ISPs)
com
Commercial organisations
org
Other organisations uk
United Kingdom au
Australia jp
Japan

19. Uniform Resource Identifier
A URI (sometimes known as a URL):
Has all the information to identify a resource
is the protocol being used
News.bbc.co.uk is the FQDN
/1/hi/sci/tech/ stm is the file path on the server

20. email address An email address consists of: The user name
A separator symbol
A domain name

21. Task (criteria P5)
You have been asked by a friend to explain how network communications work in a company. Describe how hardware, software and addressing combine to use a web browser to send an to another system.
Include a diagram making sure you show how the components are connected together
Make sure you explain:
NIC, cable, switches, routers, modems, servers
NOS, client, web browser
IP and MAC addresses