Your ip address is what allows you to communicate with other networks. Believe it or not, the Internet as a whole is comprised of a vast number of networks. Mine is online, BigMatt's home office is online. Yours is online, if you are reading this... A community of networks makes up the mesh that we call: The Internet. Having said that, the internet is more than just the fun World Wide Web. It has a vast number of protocols as well. FTP, HTTPS, SFTP, SMTP, POP, IMAP just to name a few. All of these protocols from many networks connected make the Internet happen; so to speak.
The importance of your IP address is as important as your home's street address. If noone knew your street address, noone would be able to visit you. This is the same with your IP address. You must have a valid Wide Area Network (WAN) IP address in order to communicate to the world via the Internet. There are ranges of IP addresses that will allow you to connect with the world. The ranges can be found here: http://www.tech-faq.com/ip-address-classes.shtml Your IP will fall into one of those classes. There are reserved ranges within these IP addresses. Specifically, 10.x.x.x (Class A), 127.0.0.x (No class per se; Reserved for localhost), 169.254.x.x (Reserved for APIPA), 172.16.x.x (Class B), and 192.168.x.x (Class C). These addresses are reserved as Local Area Network (LAN) IP addresses. My computer has a 192.168.x.x IP address but my WAN IP is something different that starts with 74.x.x.x This is how IP addressing has evolved. Mainly due to the fact that with the current IPv4, we have run out of WAN IP addresses. Thus by reserving a set amount of IP addresses that networks can use behind firewalls, will increase how many computers can connect to the Internet. I'm not going to discuss the details of NAT and all of the other things needed to make this happens. Let's talk about the importance of your subnet mask. Your subnet mask is coupled with your IP addresses so your IP address knows which network it's on and can communicate with. A typical 192.168.x.x subnet mask is 255.255.255.0 What does that mean? A subnet mask is broken into 4 different octects. Each octet has have a total of 8 bits that can be broken out into binary terms. More on that can be found here: http://en.wikipedia.org/wiki/Subnetwork Once all of the bits are used (255) then no more hosts can assigned on that network. All of the bits are being used for the network. This is what I mean, with a range of IP's such as 192.168.x.x 255.255.255.0, you can assign 65025 hosts. That's because you are able to alter the IP address from 192.168.0.0 all the way to 192.168.255.255. There are some quirks even with that but you get the idea. Now let's look at what you can do with another LAN IP. 172.16.0.0 255.255.0.0 can be assigned all the way up to 172.31.255.255. I am able to alter the number in the second octet to allow more LAN IP's. That's because more hosts are available with 255.255.0.0 when compared to 255.255.255.0. More of the bits are allocated for hosts and not network using the latter. Having said that you can make the subnet mask have less available IP's by using more of the bits for network i.e. 255.255.255.252. This will allow 4 hosts and is generally used to make connections over WAN's. This is to keep potential hosts to a minimum on the network. What I mean is once the octet has been assigned 255 then that particular octet has locked the IP address's octect for communication purposes. 192.168.1.x 255.255.255.0 With that assignment, no other IP outside of a 192.168.1 address can communicate with it. However if the IP addresses are: 192.168.1.100 255.255.255.0 192.168.1.101 255.255.255.0 These IP addresses will be able to communicate because they are on the same subnet (network). These IP addresses will NOT be able to communicate because they are on different subnets (networks): 192.168.1.100 255.255.255.0 192.168.2.101 255.255.255.0 Notice in the third octet of the IP address I changed the number to 2. That means I'm on another network since all of my hosts bits are being used in the same octet as my subnet mask. If I changed the subnet mask to something like this: 192.168.1.100 255.255.252.0 192.168.2.101 255.255.252.0 Then I'll be able to communicate since we are now on the same network. There is much more detail that you can find on the internet of how to correctly subnet a network, but I'm not interested in the discussion here. I hope this answers most of your questions as to how IP addresses work and subnet masks. I didn't dive into CIDR b/c I didn't want any confusion. I prefer CIDR but that's another topic too. I did most of this off the top of my head, so anyone feel free to correct anything that needs it. A great reference card for subnetting: http://en.wikipedia.org/wiki/Image:Subnetting.png Cheers, Matt www.crossloop.com/matthewbramer On Oct 13, 9:40 am, vjdash <[EMAIL PROTECTED]> wrote: > Hello all! > I want to know some networking basics. > What is the significance of the "IP address" and especially the "IP > subnet mask"? > Is the significance of the IP subnet mask limited upto the local IP > server? Or is it significant on another server which is bridged or > connected to the local IP server? > How is the subnet mask address assigned? > What is the meaning of the sub-fields of the IP subnet mask? > Thanks! > vjdash > Oct 13, 2008. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Computer Tech Support" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/computer-tech-support?hl=en -~----------~----~----~----~------~----~------~--~---
