How do you decide a major network IP address subnet mask?

[cb7a1cd0]

So here my requirement was 245 hosts, so I thought /24 subnet mask would do the job. But it didn't. I am not sure why? I asked in few other forums and their response was /24 doesn't cover 192.168.1.x. Which is for sure true. But how do you know what subnet mask to choose for major network beforehand? Is it hit and trial?

[dark_pyrro]

Why wouldn't /24 work for 192.168.1.0? Should be no problem. There's no "hit and trial" in subnetting, it's all based on logic.

[cb7a1cd0]

6 hours ago, dark_pyrro said:

Why wouldn't /24 work for 192.168.1.0? Should be no problem. There's no "hit and trial" in subnetting, it's all based on logic.

/24 would cover from w.x.y.0 to w.x.y.255

[dark_pyrro]

I can't really see what your problem is. If you configure a network to use 192.168.1.0/24 (or a 255.255.255.0 subnet mask) you will get 254 usable addresses. Not sure why you want 245 usable addresses, but anyway, why complicate things? Just set the network up with 192.168.1.0/24 and if, for some reason, you only want 245 addresses then "limit" it using DHCP (not a true limit really but a way to achieve some kind of limitation on available addresses).

[cb7a1cd0]

1 hour ago, dark_pyrro said:

I can't really see what your problem is. If you configure a network to use 192.168.1.0/24 (or a 255.255.255.0 subnet mask) you will get 254 usable addresses. Not sure why you want 245 usable addresses, but anyway, why complicate things? Just set the network up with 192.168.1.0/24 and if, for some reason, you only want 245 addresses then "limit" it using DHCP (not a true limit really but a way to achieve some kind of limitation on available addresses).

dude what are you telling? lol. thanks for trying to help though.

I have 60*4+5 hosts=245 hosts.

Do you know how many ip addresses /24 subnet mask gives?

 

[dark_pyrro]

Well, I still can't see the problem here. If you need a network that can accommodate 245 devices (or, be able to handle 245 IP addresses), then using a /24 network will do it for you since it will allow 254 usable IP addresses in that network. And, 245 is less than 254 right. If you want to use 192.168.1.x as a "base" for that network, then 192.168.1.0/24 will provide you with a range that will host (at least) 245 IP addresses. You have to explain your scenario more in detail since there is no issue here as I see it.

For example, use this subnet calculator
https://www.calculator.net/ip-subnet-calculator.html

In the "IPv4 Subnet Calculator" section, add:
Subnet = 255.255.255.0/24
IP Address = 192.168.1.0
Click "Calculate"

In the result, look for
"Number of Usable Hosts" (which is 254)

Which means there's room for 245 hosts withing that range of 254 usable IP addresses.

[cb7a1cd0]

2 hours ago, dark_pyrro said:

Well, I still can't see the problem here. If you need a network that can accommodate 245 devices (or, be able to handle 245 IP addresses), then using a /24 network will do it for you since it will allow 254 usable IP addresses in that network. And, 245 is less than 254 right. If you want to use 192.168.1.x as a "base" for that network, then 192.168.1.0/24 will provide you with a range that will host (at least) 245 IP addresses. You have to explain your scenario more in detail since there is no issue here as I see it.

For example, use this subnet calculator
https://www.calculator.net/ip-subnet-calculator.html

In the "IPv4 Subnet Calculator" section, add:
Subnet = 255.255.255.0/24
IP Address = 192.168.1.0
Click "Calculate"

In the result, look for
"Number of Usable Hosts" (which is 254)

Which means there's room for 245 hosts withing that range of 254 usable IP addresses.

https://superuser.com/questions/1728423/generally-major-network-subnet-mask-is-given-for-subnetting-how-would-you-calcu

i answered it here myself. take a look at that, that's what i'm talking about.