Computer network is the way computers connect to each other or other computers within the local network (LAN) or using the World Wide Web (WWW – the internet) to connect to distant computers, websites, or any other service we want to reach.

The Computer Network itself is a collection of computers connected together, or at least accessible from each other in one way or another. The internet as we call it is a collection of computers that each gives us different service, websites, ftp, or any other service we might get from a distant computer or company. Those computers have a leg (cable) outside of their own LAN (local area network), which enables us to access it from outside.

When we look at a home computer (to simplify the network configuration) the basic connection configuration to the internet is “computer” –> “router/firewall” –> modem –> ISP (internet service provider). The way we can access it from the outside, is by asking for a permanent IP from the ISP (which will always point to our home computer) and on our network enable access from that IP inside to the local computer’s IP on our LAN using rules in our router/firewall so that access will be enabled and secured. When this last process is done, our computer will be accessible from the internet (from outside). This configuration is the basic network infrastructure which every computer on the network will have with different types of equipments and configurations but the basic will be the same.

• I am not going to go over the network configuration chart, since this article is about network help, and as such I would like to specify the main network problem issues that might occur, and how to get help to solve them.

The IP – the network has all of those devices attached to it, and in order to be able to reach each device independently, the network distributes IP’s to any device, computer, appliance that is being connected to the network. Such IP is unique to that device, so if you are connected to the network, your computer should have an IP. The way to check your IP, is to do:

• Windows:

o    start –> run (then hit the ENTER key).

o    Type cmd (then hit the ENTER key).

o    On the command prompt (black screen that opens) type ipconfig – (then hit the ENTER key)

o    This will display a list of IP’s – so if you are on your local LAN, the IP will be one of the IP’s on that LAN network IP range.

o    So if you got an IP numbers on that list, you are connected to your local LAN.

• Linux:
  

o    Just type ifconfig – (then hit the ENTER key)

o    You will receive the list of IP’s

o    So if you got an IP numbers on that list, you are connected to your local LAN.

• So now that we have some basic tools to check things, we will be able to use them to conduct certain tests and checkups when a network issue occurs.

Some basic network problems you might stumble upon:

1)    The internet is not accessible – You can’t browse the internet.

a)    Try unplugging the modem from the electricity, and re-plugging it (this will force it to check/renew its IP from the ISP).

b)    Try unplugging the router/firewall from the electricity, and re-plugging it back in – (in case the router got stuck for any reason).

c)    Call the support line of the ISP your connected through, and ask them to check:

• If they can see your equipment – if they can see the modem is replying.
• Is the user/password they gave you to connect to the internet is still valid and operational. (We all get a user/password from the ISP to connect to the internet, sometimes there are problems with that user (maybe the payment was not received and the user was blocked/cancelled etc…)).

2)    You want to connect to a network printer – On windows it is usually pretty simple and it is being divided into two types of printers:

a)    A network printer – that has an IP on the network

1. Start –>control panel
2. Printer and faxes
3. Add a printer
4. Press next
5. Choose the “local printer attached to this computer” – (don’t tag the “automatically detect…”).
6. Press next
7. Select the “create a new port” below – and choose from the drop down selection box, the “Standard TCP/IP port”
8. Press next then another next
9. Type the IP of the network printer on the “Printer name or IP address” field.
10. Press next
11. You might be requested to install the printer driver or choose from Microsoft Windows printers, so just browse to the location of the printer driver, either on a folder anywhere or on the DVD Rom drive, to install the printer driver.
12. Now, the printer will be added to your printers on your local computer, and you will be able to use it.

b)    A USB printer – that is connected to a computer which has an IP on the network.

i)    On the computer that the printer is connected to, you have to go to:

1. Start –>control panel
2. Printer and faxes
3. Right click the printer – and choose “sharing” – follow the instructions and the printer will be able to be seen by other network users.

ii)    On the distant computer – all you need to do is the following:

1. Start –> run
2. “\\ip of the computer that the USB printer is attached to it” then press “ENTER”
3. Now you will see the printer on the list retrieved from that computer.
4. Right click that printer – select “connect”
5. Now it might request to install the printer’s driver (which you should either have a CD, or a driver suitable to your operating system somewhere on the network), use that file in case the system requests the place for the driver.
6. Now, that shared printer will be on your printers list, and you will be able to print to it.

3)     Sharing a folder between computers on the same network – When you want to copy files from one computer to the other, a good way to do so, is just share a folder from one computer to the other.

a)    You open your “my computer” – or do CTRL+E – to open the file explorer.
b)    You go through the folders until you find the folder you want to share, or just create a new one.
c)    When you find that folder, right click it
d)    Choose “sharing and security”
e)    On the “sharing tab” click on the “network sharing and security” the “network setup wizard”
f)    This will open a new window, so just follow the instructions
g)    Press next till you reach the “select a connection method” select the “this computer connects to the internet through a residential gateway….”
h)    Press next on the naming and on the workgroup name – leave it on “MSHOME” which is the default (if you’re on a domain – you will place your organization’s domain name (xxx.com).
i)    Then you’re done.

j)    To access that shared folder, anyone else needs to just do:

1. Start –> run
2. “\\ip of the computer IP that the shared folder is on” and press “ENTER”
3. Then you will see the folder, and you will be able to access it
4. Remark: most likely you will be requested to enter a user/password – so just type a user/password of that remote computer, and you’re done.

These are the basic network issues which anyone might have to deal with. I have attached another link of such network cases and solutions, so you can review – http://www.computerhope.com/help/nic.htm

The network help you can get, other then those basic issues I have specified here, are from professionals. Either through an online Internet support websites, or just call a local computer technician, that can come and help you find the problem and solve it for you.

Active Directory is a package designed by Microsoft to manage an organizational network, this package is using different tools to organize and manage the corporate network. Basically before we get into specifics, the Active Directory is creating a managerial environment, where all of the network clients (end users) are connected to it, and anyone who connects to it is registered and monitored by the Active Directory system. That enables it, to manage the end users, what they are allowed to do, what they can’t, which resources will be available to whom. It creates groups and give those groups policies (group of rules) which binds that group into those rules, and every end user that is defined within this group is bind by it rules, and accordingly can or can’t do things within the network.

The Active Directory, has been built inside the windows servers (server 2003, 2008) and the Active Directory is it’s source of organization. Anyone who connects to the server is actually connected to the Active Directory, and through that can use the network resources, as defined in the Active Directory rules.

So how does it work ?
The tools that Active Directory uses, are the LDAP (lightweight directory access protocol) which is basically a library service. There is the authentication protocol based on Kerberos (authentication protocol for client/server services that enables connection and communication using secret encrypted codes over the internet), then there is the DNS (domain name system, which translate names like website addresses into IP addresses) and finally the group enforcement, making sure the group rules are working properly.

The Active Directory has a Physical aspect which includes a database that is residing on DC (DomainControllers), those DCs can do various operations and purposes, or the same operation for redundancy and loading performance and separations, where each change in domain is replicated using a replication mechanism, to the other domains and of course updating the whole organization accordingly. The Logical aspect of it is hierarchical concepts, like a pyramid, the higher structure is a forest, which is containing trees which resemble a collection of DCs. The forest is actually any object on the network, anything connected to it, and the rules apply using that hierarchy.

Each object on the network is an “Entity” and each entity has its own definitions which divides into 3 types: resources, services & users. Every object has it’s unique GUID (ID), which identifies against the library (the LDAP) and that is how it gets identified.

This is the basic operation of the Active Directory. It’s use and functionality is to centralize manage all of the computerized resources in the organization. The policy can be implemented using a management tool called GPO (group policy) which can manage the policies given to different groups in the organization’s network.

This whole concept enable the network administrator to obtain control over the whole network from one computer (DC) and  to define what type of desktop will a user have, which directories he can access, what tools he can use etc…