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Security of The Network and Reduces The Size of The Broadcast Domain

Subnetting involves dividing a network into smaller networks. It improves routing efficiency, security, and reduces broadcast domains. The network ID identifies devices on a network and ensures security. The broadcast ID enables transmission to all nodes on a local network and is the highest numeric value. When subnetting an IP address, the subnet mask is combined with the IP address to split it into a network address and host address. There are two primary methods for subnetting - the table method which is used to subnet a single IP address into multiple networks, and the octet method which is used to determine the subnet mask, network, and range for a set of IP addresses.

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135 views2 pages

Security of The Network and Reduces The Size of The Broadcast Domain

Subnetting involves dividing a network into smaller networks. It improves routing efficiency, security, and reduces broadcast domains. The network ID identifies devices on a network and ensures security. The broadcast ID enables transmission to all nodes on a local network and is the highest numeric value. When subnetting an IP address, the subnet mask is combined with the IP address to split it into a network address and host address. There are two primary methods for subnetting - the table method which is used to subnet a single IP address into multiple networks, and the octet method which is used to determine the subnet mask, network, and range for a set of IP addresses.

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SUBNETTING

Subnetting is the practice of dividing a network into two or more smaller networks. It increases routing efficiency, enhances the
security of the network and reduces the size of the broadcast domain.

Network identity (network ID) is a portion of the TCP/IP address that is used to identify individuals or devices on a network such
as a local area network or the Internet. Network ID is designed to ensure the security of a network and related resources.

Broadcast ID is an address that enables transmission to every node in a local network. The address is the highest numeric value of
the address format being used. ... An IP broadcast address is the highest number in its class; for example, the broadcast address of
a Class C 192.168.16.0 network is 192.168.16.255.

The network ID is used by routers so they have something like any address belong to 192.168.1.0/24 network send it over to this
router. The Broadcast ID is used by nodes as the destination address when they want to send a broadcast like ARP requests.

A subnet mask neither works like an IP address nor does it exist independently of them. Instead, subnet masks accompany an IP
address and the two values work together. Applying the subnet mask to an IP address splits the address into two parts, an
extended network address, and a host address.

1. If the given is ONE IP ADDRESS TO SUBNET, use the TABLE METHOD.


2. You can also use TABLE METHOD if you want to determine the NETWORK ID, BROADCAST ID and USABLE HOST ID/
RANGE.
3. If you will determine the SUBNET MASK, NETWORK and NETWORK RANGE of a given set of IP ADDRESS or NETWORK,
use OCTET METHOD.

Example 1

REMEMBER: SHS - Senior High School

Given: 192.168.10.0/26 will be divided into 3 networks


Note: In using the table method select the subnet enclosing the given number of networks to be divided.

64 – 2 = 62

Now, we will use this column, since we will subnet an IP address into 3 subnets. Now we will make a subnet table containing the
Following: NETWORK ID, SUBNET MASK, USABLE HOST ID RANGE, # USABLE ID, and BROADCAST ID.

NETWORK ID SUBNET MASK USABLE HOST ID RANGE # USABLE HOST ID BROADCAST ID


192.168.10.0 /26 192.168.10.1 - 192.168.10.62 62 192.168.10.63 1
1192.168.10.64 /26 192.168.10.63 - 192.168.10.126 62 192.168.10.127 2
192.168.10.128 /26 192.168.10.129 - 192.168.10.190 62 192.168.10.191 3
192.168.10.192 /26 192.168.10.191 - 192.168.10.254 62 192.168.10.255

Example 2
To solve this kind of problem, trial and error is applied using OCTET METHOD.

OCTET METHOD

To get the equivalent subnet mask, just add the exponential equivalent of two remaining bits, therefore the equivalent
subnet mask for 192.168.10.0/26 is 255.255.255.192
And the number of host ID is the exponential equivalent of the last bit, which is 26 = 64

64 – 2 = 62 No. of usable HOST ID

Now, the answer to the given problem is /28: showing the solution

8 8 8 4 24 = 16 interval

Since all the given addresses belong to the same IP address class. Just focus on the last octet.

We have 33 -47 on the first network and 49- 62 on the second network.

Network ID Usable ID Range Broadcast ID


n.0 n.1- n.14 n.15
n.16 n.17 – n.30 n.31
n.32 n.33 – n.46 n.47 1
n.48 n.49 – n.62 n.63 2
The given set of IP addresses must be in different networks but within the usable ID range.

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