Trying to figure out how to figure

[gporter]

Trying to figure out how to figure this out.
128,64,32,16 =240
256-240=16
This leaves a 48-64 span. 49 1st host, 62 last. 63 broadcast addr.

Is this right
Meaning the answer would be "c"

Which IP address range is allowable given an IP address of 172.37.2.56 and 12-bit subnetting?

a. 172.37.2.48 to 172.37.2.63
b. 172.37.2.48 to 172.37.2.62
c. 172.37.2.49 to 172.37.2.62
d. 172.37.2.55 to 172.37.2.126

 

[davidbeecken]

Appears right to me, btw a little tip, instead of doing
256-240=16

Just take the last bit used 128,64,32,16
which is 16. Thats your incremental var

 

[CCIEWANNABE]

Address: 172.37.2.56
Netmask 255.255.255.240 = 28 12 bit subnets (2*N)-2
Network: 172.37.2.48/28
Broadcast: 172.37.2.63
HostMin: 172.37.2.49
HostMax: 172.37.2.62
Hosts/Net: 14
Subnet bit mask : 10nnnnnn.nnnnnnnn.ssssssss.ssss[/red]hhhh


10nnnnnn.nnnnnnnn.is mask of B class address
ssssssss.ssss[/red]= "12-bit subnetting?"
h = host bits remaining.
Route once; switch many