subnetting, first usable address?

[mocchi]

Hi guys.. i got a subnetting question

actually before i start, i may be in the wrong forum.. if i am im sorry.(please move it)

okay here we go.

network address: 93.0.0.0 /19

what would be the first usable subnet?

a) 93.0.0.1 to 93.0.31.254?

b) 93.0.32.1 to 93.0.63.254?

also if you can please state why.

thanks.

[Smilin]

If you google for a subnet calculator, some will show you how it's worked out along with the first, to the last usable subnets

[semper]

While using a subnet calc is nice to use in the field, but what if you don't have access to one? Also if he is studying for his Network+ or CCNA, he won't be able to use it.

Now onto the question

network address: 93.0.0.0 /19

what would be the first usable subnet?

a) 93.0.0.1 to 93.0.31.254?

b) 93.0.32.1 to 93.0.63.254?

Answer is A

Why?

if you convert the subnet mask into binary you get
11111111.11111111.11100000.00000000 = (255.255.224.0)

the next thing we need to be concerned with here is the last 1

on a sheet of paper (remember these) write down
128 64 32 16 8 4 2 1

Since this is a /19 network the only part of the octet were are concerned with is the 11100000

128 64 32 16 8 4 2 1
1 1 1 0 0 0 0 0


the last 1 falls under the 32. So your usable network is 93.0.0.1- 93.0.31.254
with 93.0.0.0 being the network and 93.0.31.255 being the broadcast
The next IP range will be 93.0.32.1 - 93.0.63.254
with 93.0.32.0 being the network and 93.0.63.255 being the broadcast

As you can see it jumps by 32 for each new network.