IPv4 Subnet Masks - CompTIA Network+ N10-007 Prof. Messer

Is there the actual math where he got that chart that I can look into? I don't understand why 10000000 would be 128 etc.

No math, just a chart. This is different than the one he uses. It's pretty easy to read.

IPV4 Cheetsheet
https://www.aelius.com/njh/subnet_sheet.html

@mary said in IPv4 Subnet Masks - CompTIA Network+ N10-007 Prof. Messer:

Is there the actual math where he got that chart that I can look into? I don't understand why 10000000 would be 128 etc.

that's a binary 10000000 = decimal 128

 0000 0000 = 0
 0000 0001 = 1
 0000 0010 = 2
 0000 0100 = 4
 0000 1000 = 8
 0001 0000 = 16
 0010 0000 = 32
 0100 0000 = 64
 1000 0000 = 128

Using this type of binary table is how you figure out the hosts vs the networks from a subnet mask.

@mary apparently forgot that this was already discussed in a previous video.

@JaredBusch I did in fact. Just watched it again.

@mary https://www.mathsisfun.com/binary-number-system.html

@scottalanmiller exactly what I was looking for!