Basics of Networking

IP ADDRESS (Internet Protocol)

Definition:  A numerical value that been assigned to a device/computer/node in order for it to join/participate/communicate in a network. IP address only has a valid combination of number 0 – 255 (which consist of 256 digits as 0 is also counted)

IP address must be unique in each device/computer/node and cannot have a duplicate in the same network. IP address usually is represented in dotted-decimal notation for example 112.243.137.100

IP address is divided into 2 purposes; one is for external (normal use) and internal (private network, localhost). The internal IP is only usable within the Local Area Network (LAN). It will not pass through the modem/router and people from outside the network normally won’t be able to connect/enter to your device through the usage of private IP. But by using Virtual Private Network (VPN), you are able to connect in between different private networks.

The example of Private Network IP:

1)      10.0.0.0 – 10.255.255.255

2)      172.16.0.0 – 172.31.255.255

3)      192.168.0.0 – 192.168.255.255

Localhost is the standard hostname given to an IP address of a loopback network interface. For example by typing http://localhost, it will redirect to the http server located inside your own server (if applicable). The localhost IP is 127.0.0.0 – 127.255.255.255

There are current 2 types of IP address that being used:

1)      IPv4 – a 32 bit address which currently been widely used and nearing exhaustion

2)      IPv6 –  recently introduced to replace the IPv4 which uses 128 bit addresses

IP address has several different Class from A – E:

Class A = 0.0.0.0 – 127.255.255.255

Class B = 128.0.0.0 – 191.255.255.255

Class C = 192.0.0.0 – 223.255.255.255

Class D = 224.0.0.0 – 239.255.255.255*

Class E = 240.0.0.0 – 255.255.255.255*

*Please note that both Class D and E IP are not usable / not suitable for normal networking

SUBNETWORK

Definition: A logical form of division / segmentation of the IP address. It helps to determine the IP address location in a large network.

For performance and security reason, IP address usually is segmented / divided into various configurations which are called Subnet Mask.

Subnet Mask usually show how many IP range that attached to that particular configuration. It also acts as a validation for IP address whether it belongs to the network or not. Below is the most common subnet mask used for a normal full block of 256 IP address:

Mask Available Subnet Available Host Per Subnet Total Usable Host
255.255.255.0 1 254 254
255.255.255.128 2 126 252
255.255.255.192 4 62 248
255.255.255.224 8 30 240
255.255.255.240 16 14 224
255.255.255.248 32 6 192
255.255.255.252 64 2 128
255.255.255.254 128 2 256

CLASSLESS INTER-DOMAIN ROUTING (CIDR)

Definition: A methodology to describe the allocation of the IP address in a network. It was created to replace the old Class A, B, and C routing scheme which helps to manage the IP exhaustion problem. It is also a conversion from the Subnet Mask.

CIDR Mask Available Subnet Available Host Per Subnet Total Usable Host
/24 255.255.255.0 1 254 254
/25 255.255.255.128 2 126 252
/26 255.255.255.192 4 62 248
/27 255.255.255.224 8 30 240
/28 255.255.255.240 16 14 224
/29 255.255.255.248 32 6 192
/30 255.255.255.252 64 2 128
/31 255.255.255.254 128 1 256
/32 255.255.255.255 1

GATEWAY

Definition:  A node stands in between for the IP address to pass through to another network. The IP address gateway functions exactly the same manner.

Gateway also can be use as a firewall or proxy to monitor and filter your incoming and outgoing packets.

Usually gateway will be the node to route your packet request to reach its destination. This will be involving a few gateways on each network depending on how far your destination is.

DOMAIN NAME SYSTEM (DNS)

Definition: Allows computer and routers to identify each other efficiently on the network.

It helps to route, convert and translate hostname into IP address. This is because human is prone to using domain name to get anywhere but in the meanwhile the computer only recognize the IP address.

So DNS helps to convert the domain name typed by the human into IP address for the computer to read. Then it will send the packets that contain the IP address throughout the gateway until it reach its destination.

MEDIA ACCESS CONTROL (MAC) ADDRESS

Definition: is a unique identifier inside the network interface card for identification purposes in a network.

It was originally set by the network interface card’s manufacturer for their manufacturing number hence MAC address is unique in every network card. MAC address is not being use to set a normal network connection. It is only will be used inside the OSI layer. An example of how a MAC address looks like 00:E0:81:BA:E6:4A

A SUBNET OF IP ADDRESS

If you got a block of IPs from the service provider, first you need to understand how the IPs is assigned inside the block (unless they have specified earlier for your convenience).

Each of the IP address subnet will contain Network ID (Identification purposes), Broadcast (broadcasting the IP throughout the network), and a Gateway. Below is an example of a 122.117.163.96/29 physical distribution:

IP Definition
122.117.163.96 Network ID
122.117.163.97 Gateway
122.117.163.98
122.117.163.99
122.117.163.100
122.117.163.101
122.117.163.102
122.117.163.103 Broadcast

In the table above, it will show that the only usable IP will be only starting from 122.117.163.98 – 102. The same configuration will apply no matter how big or small the IP subnet your are getting from the service provider.

ASSIGNING IP ADDRESS

When installing a new server, normally an IP address needs to be set in order for the server to be connected to the network. The most important information that needs to be prepared when getting the server connected to the network is:

1)      IP address – identify your server on the network

2)      Subnet mask – verify the IP address grouping

3)      IP gateway – provides the entry to the network

4)      DNS – resolves domain/host name to IP address

As been mentioned earlier, all these components have its own function and how they relate to each other to make the server connected to the network. Failure to provide or wrong set of configuration, the server won’t be able to connect to the network.

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