Saturday, February 26, 2011

Diff Bet Internal, External, Public, Private, Static and Dynamic IP address.



Private IP addresses exist to save on the limited number of available public IP addresses. There are actually 4 ranges of private addresses: to when you need a lot (16,000,000+) of addresses in your internal network; to when you need up to a million or so; and to or to when you only need up to 254 addresses. These addresses must exist behind a router or gateway, not on the live Internet. 

The real genius of these private IPs is that you can get one IP from your ISP (let's say, and your router / gateway basically splits that into however many internal (private) addresses you need.

A public IP address makes your equipment accessible to everyone on the internet and is needed for VoIP or if you want to give others to access to specific equipment on your network. You must therefore be careful to protect your equipment from hackers and viruses and not to allow your equipment to be hi-jacked and used as an open email-relay, for example. A private IP address is for private use within the network and allows many more PCs to be connected. If a customer is using a private IP and later wants VOIP they would need to change to a public IP address.
A static IP is one that will never change. A dynamic IP is exactly that, dynamic. It could change frequently, or not change for more than 1 year. It really depends on how the DHCP server that’s assigns the IPs is set up.