Need to figure out a subnet.

WellingtonIS
WellingtonIS used Ask the Experts™
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I have a range of IP's a beginning and and end how can I figure out the subnet?  209.182.170.239-254
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IP range is usually decided by the number of hosts you like to have in a subnet let suppose you need 30 hosts in a particular subnet then you will use 192.168.1.0-192.168.1.32 which contains 30 hosts and move forward

Author

Commented:
Well I understand that but I was given the range I'm just trying to figure out the subnet
What about if you try the experts exchange tool. https://www.experts-exchange.com/tools/subnet-calculator.html
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atlas_shudderedSr. Network Engineer

Commented:
The network range will be between a /24 and a /27.

What is the default gateway for the IPs they have given you?
nociSoftware Engineer
Distinguished Expert 2018

Commented:
/27 is the smallest subnet, /0 (the internet) the largest describing this network.

Commented:
It'll be a /28 or 255.255.255.240

You can always use the following: http://www.subnet-calculator.com/cidr.php

Enter in the ending IP address and change the CIDR and see what value the beginning and ending IP addresses falls in
nociSoftware Engineer
Distinguished Expert 2018

Commented:
@coolie sheppard,   it really needs a /27... (/28 start @ 240 and end on 255) so 239 is still missing out.
atlas_shudderedSr. Network Engineer

Commented:
Again, The network range will be between a /24 and a /27.  Scope is a Class C so mask will be nothing larger than /24.  Due to the range of the provided IP's, the mask cannot be larger than /27 as anything smaller will fall across the S/N boundary, so it cannot/will not be a /28.

It also does not have to be a /27.  The default gateway is going to tell a lot about the mask size.  Even better, the ISP.
nociSoftware Engineer
Distinguished Expert 2018

Commented:
Search on address deleiverd this:
Your ISP obtained a /20 block and probably carved it into smaller blocks (class has nothing to do with /CIDR....)
If it is a class block it is /24...
at it's own it needs a /27 (at minimum blocksize) and can be as large as /20 within this ISP.  (then you would have the complete block...)
(after the  the / a smaller number means a more hosts).
Addresses after this range would not get routed to your ISP ans thus not to you.

NetRange:       209.182.160.0 - 209.182.175.255
CIDR:           209.182.160.0/20
NetName:        AMERI-43
NetHandle:      NET-209-182-160-0-1
Parent:         NET209 (NET-209-0-0-0-0)
NetType:        Direct Assignment
OriginAS:       AS13628
Organization:   AMERISOURCEBERGEN (AMERI-43)
RegDate:        2016-04-14
Updated:        2016-04-18
Ref:            https://rdap.arin.net/registry/ip/209.182.160.0
nociSoftware Engineer
Distinguished Expert 2018

Commented:
/28 is not correct.   (that is 240-255, or 224-239)   it does not contain   both 239 & 254.
AlanConsultant

Commented:
I have to agree with Noci and atlas_shuddered - WellingtonIS has marked as a solution, an answer that is demonstrably incorrect.

This cannot be a /28.

209.182.170.240 / 28 (or mathematically, up to and including 209.182.170.255 / 28) gives you:

209.182.170.240 through 209.182.170.255 inclusive

It excludes 209.182.170.239 which WellingtonIS explicitly said must be included - refer to their question:

I have a range of IP's a beginning and and end how can I figure out the subnet?  209.182.170.239-254


For anyone reading this later - please disregard WellingtonIS, and do not follow the solution they have marked as correct.


Thanks,

Alan.

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