fortypoundhead.com

Why Do We Need Private Address Ranges?

Posted On 2008-01-18 by FortyPoundHead
Keywords:
Tags: Cisco Networking Tutorial 
Views: 1516


When you''re studying to pass the CCNA, you''re introduced to "private addresses", the address ranges formally referred to as RFC 1918 Private Addresses. (RFC stands for Request For Comment; to see a typical RFC, just put that term in your favorite search engine.)

There are three ranges of 1918 Private Addresses, one in each major network class.

Class A: 10.0.0.0 /8

Class B: 172.16.0.0 /12

Class C: 192.168.0.0 /16

Be careful - these masks are not the classful network masks you''re familiar with!

The need for private address ranges arose when we started running out of IP addresses. (A lot of us never thought that would happen, but a lot of us used to think wed never need storage units bigger than floppy disks, too.) You can imagine that as networks began to be installed in offices and schools worldwide, the finite number of IP addresses became a restrictive factor.

Many devices that were using these precious IP addresses did not need to communicate with any device outside its own local area network (LAN). Therefore, these devices could be assigned an IP address that could be used on another device in another LAN - but these devices would not be able to communicate across the Internet.

It was decided to create network address ranges that would be used exclusively for such devices. That''s why when you go from one local area network to another, you''ll usually see hosts with IP addresses from the above three ranges.

Of course, as time went on, more and more of these devices did need to reach hosts across the Internet. That''s where NAT - Network Address Translation - comes into play. But that is a subject for another tutorial!


About the Author

FortyPoundHead has posted a total of 1974 articles.

 


Comments On This Post

No comments on this post yet!


Do you have a thought relating to this post? You can post your comment here. If you have an unrelated question, you can use the Q&A section to ask it.

Or you can drop a note to the administrators if you're not sure where you should post.


Your IP address is:54.80.10.56

Before you can post, you need to prove you are human. If you log in, this test goes away.




Recent Forum Posts

Advanced search added
dwirch posted on September 23, 2017 at about 13:44 in Site News

Job Spammer: Gaurav Mehta - AgreeYa Solutions
dwirch posted on September 22, 2017 at about 10:35 in Spammers

Job Spammer: Prutha Siri - Javelin Systems
dwirch posted on September 10, 2017 at about 6:15 in Spammers

New security implemented
dwirch posted on September 7, 2017 at about 7:16 in Site News

Malicious IP Checker Companion Tool
dwirch posted on August 12, 2017 at about 20:24 in Site News

Job Spammer: Steve Adams
dwirch posted on August 8, 2017 at about 7:44 in Spammers