Subnetting and mask address:

[dehlert]

I asked a question similar to this earlier but then realized when I subnetted, it only gave me 126 hosts per subnet.

10.11.12.0/23 network address

I now have it in the 4 networks as follows:
10.11.12.0/25

default gateway:
10.11.12.0

Subnet 1:
10.11.12.0/25

Server address:
10.11.12.1
Ip address range:
10.11.12.2-10.11.12.254
subnet mask:255.255.255.128
broadcast: 10.11.12.255

Subnet 2:
10.11.13.0/25

Server address:
10.11.13.0
IP address range:
10.11.13.1-10.11.13.1-10.11.13.254
Subnet mask: 255.255.255.128
Broadcast: 10.12.13.255

Subnet 3:
10.11.14.0/25

Server address:
10.11.14.0
IP address range:
10.11.14.1-10.11.14.254
Subnet mask:255.255.255.128
Broadcast: 10.11.14.254

Subnet 4:
10.11.15.0/25

Server address:
10.11.15.0
IP address range:
10.11.15.1-10.11.15.254
Subnet mask: 255.255.255.128
Broadcast: 10.11.15.255

I'm just starting networking and I don't know know if I'm on the right track as subnetting is hard for me to grasp. Can someone let me know if this would be a correct setup and if not why. Any help is appreciated.

 

[Sylvvester]

It would make more sense if you used masks: /22 and /24 for subnetwork
Otherwise the sub networks should be:
10.11.12.0/25 ip range: 10.11.12.1 - 10.11.12.126, broadcast: 10.11.12.127
10.11.12.128/25 ip range: 10.11.12.129 - 10.11.12.254, broadcast: 10.11.12.255
10.11.13.0/25 ip range: 10.11.13.1 - 10.11.13.126, broadcast: 10.11.13.127
10.11.13.128/25 ip range: 10.11.13.129 - 10.11.13.254, broadcast: 10.11.13.255

 

[dehlert]

It would make more sense if you used masks: /22 and /24 for subnetwork
Otherwise the sub networks should be:
10.11.12.0/25 ip range: 10.11.12.1 - 10.11.12.126, broadcast: 10.11.12.127
10.11.12.128/25 ip range: 10.11.12.129 - 10.11.12.254, broadcast: 10.11.12.255
10.11.13.0/25 ip range: 10.11.13.1 - 10.11.13.126, broadcast: 10.11.13.127
10.11.13.128/25 ip range: 10.11.13.129 - 10.11.13.254, broadcast: 10.11.13.255

That only gives me 126 hosts per subnet though right? I need one subnet with 254 hosts max.

 

[bill001g]

That is why he said to use a /22. A /23 only has 512 address. Ignoring this has anything to do with ip address 512 divided into 4 parts is still 128.

 

[dehlert]

That is why he said to use a /22. A /23 only has 512 address. Ignoring this has anything to do with ip address 512 divided into 4 parts is still 128.

Thanks! So it should be the following then correct?

10.11.12.0/22

default gateway:
10.11.12.0

Subnet 1:
10.11.12.0/22

Server address:
10.11.12.1
Ip address range:
10.11.12.2-10.11.12.254
subnet mask:255.255.252.0
broadcast: 10.11.12.255

Subnet 2:
10.11.13.0/22

Server address:
10.11.13.0
IP address range:
10.11.13.1-10.11.13.1-10.11.13.254
Subnet mask: 255.255.252.0
Broadcast: 10.12.13.255

Subnet 3:
10.11.14.0/22

Server address:
10.11.14.0
IP address range:
10.11.14.1-10.11.14.254
Subnet mask:255.255.252.0
Broadcast: 10.11.14.254

Subnet 4:
10.11.15.0/22

Server address:
10.11.15.0
IP address range:
10.11.15.1-10.11.15.254
Subnet mask: 255.255.252.0
Broadcast: 10.11.15.255

 

[Sylvvester]

No. Subnets need to use /24 mask (255.255.255.0).
Also what's with that default gateway? 10.11.12.0 is a network address and can not be assigned to a device like a router.

 

[dehlert]

No. Subnets need to use /24 mask (255.255.255.0).
Also what's with that default gateway? 10.11.12.0 is a network address and can not be assigned to a device like a router.

Thanks for bearing with me on this. I think I just need to start over then as using a /25 I believed would give me in binary:
11111111.11111111.11111111.10000000
which translated to:
255.255.255.128

I guess I need to start the book all over again to grasp this...

 

[Clayto1332]

Okay... Here you go.

10.11.12.0/22 is the block of addresses you need...

Subnet 1:
10.11.12.0/24

Subnet 1 gateway:
10.11.12.1
Left over useable IP address range:
10.11.12.2-10.11.12.254
subnet mask:255.255.255.0
broadcast: 10.11.12.255

Subnet 2:
10.11.13.0/24

Subnet 2 gateway:
10.11.13.1
Left over useable IP address range:
10.11.13.2-10.11.13.254
Subnet mask: 255.255.255.0
Broadcast: 10.12.13.255

Subnet 3:
10.11.14.0/24

Subnet 3 gateway:
10.11.14.1
Left over useable IP address range:
10.11.14.2-10.11.14.254
Subnet mask:255.255.255.0
Broadcast: 10.11.14.255

Subnet 4:
10.11.15.0/24

Subnet 4 gateway:
10.11.15.1
Left over useable IP address range:
10.11.15.2-10.11.15.254
Subnet mask: 255.255.255.0
Broadcast: 10.11.15.255

Note that your gateway doesn't have to be particularly the first available IP address in each subnet. On a /24, an IP address that ends with a .0 will ALWAYS be your network ID and your useable IP address range will be from .1 to .254. You can make your gateway or whatever servers and devices you have on the network whatever you want within that range.

Remember, a /23 will hold two /24 subnets. A /22 will hold two /23 subnets. SO a /22 can fit four /24 subnets within it.

Also keep in mind that a block of IP addresses you have will not particularly have a default gateway assigned to it. If you are given a block of IP addresses that you are dividing into more than one subnet, each subnet will have its own unique default gateway and will have to be within its own useable IP address range.