Network + : Damelin College Mowbray

So, I am studying the N+ course through Damelin and have decided to use my blog as a medium to summarise lessons that I and my classmates can use as a reference to help with studying! I hope that my fellow classmates make use of it and also find it useful - all feedback will be appreciated!

Lesson 1

The OSI model (Open System Inter-connect): this is a 7 layered model which covers all the aspects in the environment of computing, the steps are as follows:

1. Physical Layer - Media, signal and binary transmission (can also be the hub or repeater)
2. Data Link - Physical addressing (The switch would fit in here)
3. Network - Path determination and logical addressing (the router would fit in here)
4. Transport - end to end connections and reliability
5. Session - Interhost communication
6. Presentation - data representation and encryption
7. Application - network process to application

1 - 3 are physical (hardware) and 4 - 7 are logical (software, services)

The OSI model would work in order of sent i.e. the sending device would send in order of 1 to 7 and the receiving device would receive as 7 to 1.

Here is some terminology that we learnt and need to know:

• Networks - To communicate and share resources which could be files, printers and email
• Network components -

1. Device - any hardware
2. Media - connects devices to the network and carries the data between
3. Network adapter - hardware that translates the data between network and device
4. Network operating system - (NOS) - software that controls traffic and resources
5. Protocol - set of rules for communications

Servers

Server is a network computer which shares resources with and responds to requests from other network computers.

Clients

Also known as a node or peer, this is a network computer which utilises the resources of other network computers. This client computer has its own processor, memory and storage.

Peers

Self sufficient computer which acts as both a server and client to similar computers on its network.

They have decentralised security and will have a DOS running (like XP) and not a NOS (Server 2003/8)

Host Computers

A powerful centralised computer system such as a mainframe computer that performs data storage and processing on behalf of clients.

TCP/IP

TCP/IP is routable (routers can and need to be used and not switches) The router recognises, for leaving the network to get to the www.

Terminals

Terminals have a chip on the network card which is called a PROM (Programmable Read Only Memory) It is a specialised network device on a host-based network that transmits the data entered by the user to to the host for processing and then displays the result ( like a bank teller) - these terminals are often called "dumb".

Authentication

This is network security measures to gain access to the network resources

• Username and passwords - usernames are usually public info and are often available, the password is secret and should be protected at all costs.

Network Directory Services

A network Directory is a a centralised hierarchical database which stores and organises data about network users and resources - we will be using MS Active Directory (all control is here)

Some important notes to remember:

• DOS, like XP is Disc operating system
• NOS, like server 2003 is Network operating system
• Persons have permissions and resources have rights
• SMTP - simple mail transfer protocol
• TCP/IP - transmission control protocol / Internet protocol
• 802.3 - ethernet
• 802.5 - token, ring environment
• 802.11 - Wireless
• Server client - provides better security and is centralised
• Peer to Peer - less security and is decentralised
• HUB or Repeater - broadcasts to everyone on the network
• Switch - has some intelligence and will remember the MAC address of computers in its network
• Router - uses TCP/IP and not MAC

There are two types of servers:

1. Member servers - provide resources such as databases (SQL, sequel server)
2. Domain Controller - Authenticates users, contains the directory services (Active Directory) which contains all users, rights and permissions

Servers need to provide:

• ACCESS
• FAULT TOLERANCE
• SECURITY
• HIGH AVAILABILITY