a question on subnetting

x_Danny_x

okay, im actually studying the CCNA and I need to refresh my memory.

lets say you have a class c address 26 bit mask. So you are going to get a value of 255.255.255.192

192 is (11000000) so the first subnet is going to start with a value of 64

the IP addresses are going to be 65-126? Cause the next network is going to start at 128 and 127 is the broadcast address. Im i correct???

Silver Bullet

From the info you provided
255.255.255.192 = Net Mask
XXX.XXX.XXX.63 = Broadcast Address
XXX.XXX.XXX.0 = Network Address
XXX.XXX.XXX.1 - 62 = Hosts Address

I could be wrong as I am not the best subnetter (If that is a word).

EDIT: Your calculation is right as well for the 2nd range......just depends on where you start.

gravyjoe

Exactly

Silver Bullet

Let's use 192.168.1.10/26
IP Address = 192.168.1.10 or 11000000.10101000.00000001.00001010

Since this is a 26 bit subnet then the 26 left most bits are used to determine the mask which will look like this.
Subnet Mask = 11111111.11111111.11111111.11000000 or 255.255.255.192

Since the subnet mask used 26 bits of our available 32 bits then we will use the remaining 6 bits to calculate the Broadcast Address and Network
Address.

For the Broadcast Address you will turn the 6 right most bits on which will look like this
Broadcast Address = 11000000.10101000.00000001.00111111 or 192.168.1.63

For the Network Address you will turn the 6 right most bits off which
will look like this.
Network Address = 11000000.10101000.00000001.00000000 or 192.168.1.0

Does that help?

Gogousa

one address after the subnet is the first usable address, one before the next subnet is the broadcast and one before the broadcast is the last usable address.