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What is an IP Address 

An  IP Address is a unique address comprised of a 32-bit number with values ranging from 0 to 4294967295 & split into four octets.  for a device to send and receive network traffic on a network.  Some devices may have more than one IP Address, because they have multiple internal components which need to communicate, or because they need to operate on multiple networks at the same time. An IP Address consists of four numbers called octets that are separated by periods. Each number can range from 0 to 255. Additional IP Addresses and ranges of IP Addresses you should be aware of: No IP Address. This is sometimes entered in the Gateway field when you want a network to be isolated. See the section on Subnets and Gateways below. (and This address always sends data back to the device that sent it. It's sometimes called localhost or a loopback address. Do not ever assign an address beginning with 127 to a device. These are Multicast IP Addresses. other IP addresses should be assumed to be part of an enterprise network which is connected to the public Internet. Do not use those addresses unless your IT Supervisor tells u too. 

What is multicast traffic?

Multicast traffic is a type of IP network traffic intended for one or more destinations. Multicast is more efficient than unicast traffic because a source only needs to send data to the network once, letting the network do the hard part. It's also less bandwidth-intensive than broadcast traffic, because only the units who want the traffic will see it. Receiving devices can be on the local network or across the Internet.  Multicast uses special destination IP addresses between and Each address is generally referred to as a Multicast Group. Traffic intended for the multicast group has a destination address of that multicast group and a source address of the device that sent it.


There are a few special groups of addresses: These are reserved for the local network which the devices are on. It won't be passed along to another subnet by a router. This range is sometimes designated as These are reserved for use by private organizations, and won't be routed over the Internet. Organizations are free to use these addresses as they see fit.

Subnet Masks & Gateways

A Subnet Mask defines which range of IP Addresses are within a local network, and which ones are not. Subnet masks always work from left to right. Devices are said to be within the same subnet if their IP Address starts with the same digits, but ends with a different set of digits. Sometimes, it's easy to tell which part of an IP address is part of the local network and which is not (when the subnet mask consists only sections that are 255 and 0), but sometimes it may not be as clear.

The very first address and very last address in a subnet are specially reserved addresses and cannot be assigned to devices. Devices that are within the same subnet will be able to communicate with one another, but a gateway is required to communicate with devices in different subnets. When traffic is intended for a device outside of the subnet, it is sent to the gateway to be routed to the correct destination. The gateway then sends the response back to the device that originally sent the request.

What is default Gateway?

When a computer on one network needs to communicate with a computer on another, it uses a router. A router specified on a host, which connects the host's subnet to other networks, is called a default gateway. This passes traffic on one subnet to devices on other subnets. This gateway often connects the local subnet to the internet.

If the subnet mask is, then the first two octets of all devices must be the same. The combination of the last two octets must be different and unique. 65,534 devices can be used in this subnet.

If the subnet mask is, then the first three octets of all devices must be the same. The 4th octet must be different and unique. A maximum of 254 devices can be used in this subnet.


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