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| Hi Guys
Question
I am having some trouble working out the IP Address range and also the Broadcast address of a given IP address and Subnet mask.
Can anyone please explain these two features of subnetting to me.
Bye. | |
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| nightdiamond 2003-09-12, 1:50 am |
| Hi,
Am trying to access the site www.learntosubnet.com but it says am not authorised to view this page. why? isn't it public?
NightDiamond | |
| martek 2003-09-12, 11:09 am |
| I have a quick and easy way of subnetting without all the binary math overhead. Here's my method:
IP address 130.45.33.13 and subnet mask 255.255.224.0. Find subnet ID, broadcast address, and valid IP range.
1. Find the increment on the last part of the subnet mask which is: 256 - last mask octet. In this case that's 256 - 224 = 32.
That tells you that subnet IDs increment by 32. So the IDs in this case go: 130.45.0.0 (subnet zero), 130.45.32.0, 130.45.64.0 and so on.
2. Now the broadcast address for a subnet is the last IP in that subnet. So in case of the 130.45.32.0 subnet that's 130.45.63.255, cause if you add 1 to 130.45.63.255 you get 130.45.64.0 which is the next subnet ID.
3. Find the first valid IP in the subnet. The first valid IP of a subnet is the subnet ID + 1, 1 added to the last octet. In case of the subnet 130.45.32.0 that's 130.45.32.1
4. Find the last valid IP in the subnet. The last valid IP in a subnet is the broadcast address for that subnet - 1. So in case of 130.45.32.0, that's 130.45.63.254, cause the broadcast address is 130.45.63.255 (see step 2).
So in case of IP 130.45.33.13 with subnet mask 255.255.224.0 that's:
Subnet ID: 130.45.32.0
Broadcast address: 130.45.63.255
Valid IP range: 130.45.32.1 - 130.45.63.254
That's it. Remember to think in terms of the increment (8, 16, 32, etc.) and it should be cake. Four easy steps and you'll be a subnetting god.  | |
| stevekohr 2003-09-12, 2:08 pm |
| Thanks martek. I'll keep practicing using your technique. Also, nightdiamond, www.learntosubnet.com is a public site, I'm not sure why you can't view it unless you have your firewall or internet security settings very high. You may have to enable cookies. I,m not sure though because I have no problem accessing the site. | |
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| for subnetting follow Todd's book by heart. trust me if you follow that book for subnetting you can get each and every question right. NightDiamond that site is ok so it must be some "Routing" problem 
search for "subnetting tutorial" in google you'll find more than you can read. if anyone have specific questions then you have this excellent forum. i wrote one subnetting
procedure in this forum. you can search it from my profile.
goodluck everyone. | |
| SureshHomepage 2003-09-14, 5:29 am |
| Learntosubnet.com is the best ever site I seen to learn IP subnetting....
I just checked the site and its okay and I do not see any password prompt as nightdiamond mentioned on this thread. | |
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. Any1 knows the IP of the site so I might perform a trace?
Just Joking 