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Likely a dumb question reguarding understanding DHCP ranges for IP's

lockit14
Level 7

So if you have a DHCP range starting at 192.168.50.2 through 192.168.50.254, am i correct in thinking that 192.168.50.115 would be WITHIN that dhcp range?   
  
  If always thought of it as more the numbers after the last "." being like decimals.  So .115 as a decimal is less than .2 as a decimal, since .2 basically means .200 
  
  I'm not sure why it never hit me that those last numbers (after the last ".") are seen as independent, so all IP's within the range of 192.168.50.2 to 192.168.50.254, are addresses such as
192.168.50.3
192.168.50. 4
192.168.50. 5
then on through 
192.168.50.10
192.168.50.18
192.168.50.34
192.168.50.115 

 and on up to 254.   
   
  So basically all this comes down to me making sure that if i wanted to reserve an IP for pc OUTSIDE the dhcp range, i would want it something like 192.168.50.350? or 192.168.50.400 ? 

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4 REPLIES 4

jzchen
Level 14

I think 254 is the upper limit, based on the encoding.  If you wanted to set one outside you could for example set the range as:

192.168.50.2 to 192.168.50.127 then put it as any of 192.168.50.128 through 19.168.50.254

Nux
Level 9

Hey lockit14.  that is a great question.  to add on to jzchen reply and to help provide more information.   " So basically all this comes down to me making sure that if i wanted to reserve an IP for pc OUTSIDE the dhcp range, i would want it something like 192.168.50.350? or 192.168.50.400 ? "

Actually depends on what is called the subnet mask.   The subnet mask determines the "Range" that is valid for the network.  
192.168.50.350 or 192.168.50.400 are both invalid.   

I great place to start is: http://www.tcpipguide.com/free/index.htm
and https://www.guru99.com/subnetting-subnet-mask.html

Yeah what I done was change the dhcp starting pool from .2 to .50, and then just reserved PC at .11    so DHCP pool now is .50 through .254

Great!

Each three digit number is represented by 8 bits.  2^8 = 256 .  That is why 255 is the upper limit including 00000000.  (The system treats .001 the same as .1, which is internally 00000001).

EDIT- To a computer/network:

1 is 00000001

2 is 00000010

3 is 00000011

255 is 11111111

(if I’m not off like a lot of my programming was)…