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Is this a valid question (related to subnetting)
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Inactive Imported Users Posts: 228
in CCNA & CCENT
This is from my Sybex book. The objective was to find the mask.
1. 192.168.100.17, with 4 bits of subnetting
Since it was a class C, I said 255.255.255.240 as the mask.
Now I know that is right. But what if the numbers were:
172.16.0.1 with 4 bits of subnetting
Would the mask change to 255.255.240.0 ?
10.0.0.1 with 4 bits of subnetting. What would the mask be then?
255.240.0.0?
Help, am I doing this wrong?
1. 192.168.100.17, with 4 bits of subnetting
Since it was a class C, I said 255.255.255.240 as the mask.
Now I know that is right. But what if the numbers were:
172.16.0.1 with 4 bits of subnetting
Would the mask change to 255.255.240.0 ?
10.0.0.1 with 4 bits of subnetting. What would the mask be then?
255.240.0.0?
Help, am I doing this wrong?
Comments

Optionssmooth7905 Member Posts: 8 ■□□□□□□□□□its 172.16.0.0 /12 so with 4 bits of subnetting it would be 172.16.0.0/16 or
255.255.0.0 
Optionsamod_pandya Member Posts: 33 ■■□□□□□□□□acc to me...you are right (the orig poster)
172.16.0.1 with 4 bits of subnetting ..mask would indeed be 255.255.240.0
Since 172.16.0.1 is a class B address it has 16 bits of network...and as 4 bits are going towards subnet it leaves 12 bits for the host so the mask should have 12 zeros or /20 as the mask or 255.255.240.0
10.0.0.1 with 4 bits of subnetting will have 255.240.0.0 as the mask.
Since 10.0.0.1 is a class A address it has 8 bits of network...and as 4 bits are going towards subnet it leaves 20 bits for the host so the mask should have 20 zeros or /12 as the mask or 255.240.0.0
hope it helps.:: PEACE :: 
Options2lazybutsmart Member Posts: 1,119yeah, I agree with amod.
If you say 4 bits, then that's 4 bits. period.
The only difference with the various classes is that 4 subnet bits would mean the same number of subnets (with the same subnet ID's) but a greater number of hosts .
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