Subnetting

• Addresses are used version 4 and consists of 32 binary bits. Every 8 bitsare separated by dotted (.).

for example :

There are 2 kinds of IP:

1. Public IP Used as a unique identity on the internet and are regulated by the IANA(Internet Assigned Numbers Authority).
2. Private IP Used for addressing the LAN (Local Area Network). Private IP should notbe used for the public because of blocked IP. Kinds of private IP addresses:

• 10.0.0.0 - 10,255,255,255 (10.0.0.0 / 8)
• 172.16.0.0 -172.31.255.255 (172.16.0.0 / 12)
• 192.168.0.0 - 192,168,255,255 (192.168.0.0 / 24)

The subnet mask is a method that indicates the IP Address and NetworkAddress. There are 2 kinds of classification IPv4 Address:

• Classfull

The value of the main dotted. For example:

Class A

00000000.00000000.00000000.00000000

/8

Network Portion Address Portion

Class B

00000000.00000000.00000000.00000000

/16

Network Portion Address Portion

Class C

00000000.00000000.00000000.00000000

/24

Network Portion Address Portion

• Classless

Value is not the main dotted.
Example:

Class C

00000000.00000000.00000000.00000000

/26

Network Portion Address Portion

Address IP Address: 192.168.10.1 / 24  defined:

• Host Address: 192.168.10.1
• IP Network Address: 192.168.10.0
• Subnet Mask: 255.255.255.0
• IP Broadcast Address: 192.168.10.255
• Range of IP Address: 192.168.10.0 - 192.168.10.255
• Range of Valid IP Address: 192.168.10.1 - 192.168.10.254 (networkaddress and broadcast address is not used).

Subnetting
Subnetting is the process of borrowing bits of host portion of a network bit,which is useful for network segmentation according to the needs of the host. Subnetting is useful also for security, for example the distribution ofbroadcast. Examples of Class C subnetting:
Network 192.168.10.0 / 24

• IP Network Address: 192.168.10.0
• Subnet Mask: 255.255.255.0
• IP Broadcast Address: 192.168.10.255
• Range of IP Address: 192.168.10.0 - 192.168.10.255
• Range of Valid IP Address: 192.168.10.1 - 192.168.10.254 (networkaddress and broadcast address is not used / no host address 254).

borrowed a bit host address, how many network address and the number of valid host addresses?

192.168.10.00000000 à borrowing 1 bit host portion

192.168.10.00000000

/25

Subnet mask :

192.168.10.0 /25 : 11111111.11111111.11111111.10000000 à 255.255.255.128

Formed:

• 192.168.10.0 / 25

IP network address: 192.168.10.0

Subnet mask: 255 255 255 128

IP Broadcast address: 192.168.10.127

Range IP address: 192.168.10.0 - 192.168.10.127

Valid range of IP addresses: 192.168.10.1 - 192.168.10.126 (126 hostaddresses

• 192.168.10.128 / 25

IP network address: 192.168.10.128

Subnet mask: 255 255 255 128

IP Broadcast address: 192.168.10.254

Range IP address: 192.168.10.128 - 192.168.10.255

Valid range of IP address: 192.168.10.129 - 192.168.10.254 (126 hostaddresses)

Thus, the formed second network address and the number of hostaddresses per subnet: 126 host addresses.

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