Remy Maza: Thanks a lot! That is so comprehensive! Sincerely, vjdash On 10/13/08, RemyMaza <[EMAIL PROTECTED]> wrote: > > > 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. > > >
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