ICND
ICNDATTEMPT
Member Posts: 8 ■□□□□□□□□□
in CCNA & CCENT
I am going to take the ICND exam next week and I am really struggling with one subnetting topic.
When you are given a subnet mask and asked which IP addresses can be assigned?
How do you go about figuring this out ? I have down all the rest of subnetting but I dont understand how to figure out IP addresses when you aren't given the subnet..but instead...just a mask ?
Do you recommend any resources ?
When you are given a subnet mask and asked which IP addresses can be assigned?
How do you go about figuring this out ? I have down all the rest of subnetting but I dont understand how to figure out IP addresses when you aren't given the subnet..but instead...just a mask ?
Do you recommend any resources ?
Comments
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kplab
Member Posts: 101
Given a subnet mask, you can tell the number of IP addresses that can be assigned per subnet (= (2^number of zeros in the subnet mask) – 2). However, you cannot tell which IP addresses can be assigned unless you also have the subnet address.KPLAB
www.kp-lab.com - Free CCNA, CCNP, and Network+ Study Guides -
Undertow
Member Posts: 48 ■■□□□□□□□□
This also sounded difficult to me a week ago but then it was really easy to understand with some practice.
When it gives you a subnet mask eg 255.255.255.248 , you subtract it with the number 256 .For exampe , 256-248=8 so the following ip addresses can be used FOR HOSTS ONLY :
a.192.168.1.9 , 149.24.1.17 and so on. 192.168.1.8 is the subnetwork address and thus cannot be used as a host address.
One subnet : 192.168.1.8
Another subnet : 192.168.1.16
Another subnet : 192.168.1.24
These addresses cannot be used for host address assignment.
Also there cannot be used broadcast addresses as 192.168.1.15 (for one subnet ) , 192.168.1.23 (for another) and so on... -
ICNDATTEMPT
Member Posts: 8 ■□□□□□□□□□
It looks like one person said you cannot figure out what the hosts would be without the subnet defined....
If you only know the subnet mask...can you figure out what the possible hosts are ? -
ICNDATTEMPT
Member Posts: 8 ■□□□□□□□□□
I understand it now...and can figure it out...I was calculating calculate the subnets but wasn't taking into account the broadcasts......
This forum is great..
I have failed the ICND test twice...844 both times....very frustrating...so close....but soo far..thanks everyone.. -
shadown7
Member Posts: 529
Yes, this forum is great!
Subnetting is a piece of cake when you get use to it. Once you've done it enough it will be as easy as breathing! 
Best of luck on your next attempt!
