Subnetting Class A - 255.255.128.0

Hi,

I'm now at the subnetting partof my studies....

Reading a few articles online (techrepublic).

Using the above subnet mask (255.255.128.0). Class A address 10.0.0.0

Is the following correct?

This gives you 512 subnets with 32,766 hosts each.

The second octet is 256-255=1, 2, 3, etc., all the way to 255.

I believe the valid host ranges for each subnet to be..

Valid host ranges for each subnet.

10.0.0.1 - 10.0.127.254
10.0.128.1 - 10.0.255.254
10.1.0.1 - 10.1.127.254
10.1.128.1 - 10.1.255.254
10.2.0.1 - 10.2.127.254
10.2.128.1 - 10.2.255.254

and so forth up to the final
10.255.128.1 - 10.255.255.254

Is this correct or am I looking at this wrong?

This is not homework or anything like that. I am just reading the following.
Subnet a Class A network with ease

Thanks

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

higherho

Since your subnet mask is 255.255.128.0 (a /17) you would not change the first two octets in your calculations.

10.0.0.1 - 10.0.127.254
10.0.128.1 - 10.0.255.254

so I'm pretty sure you should stop here.

control

higherho wrote: »

Since your subnet mask is 255.255.128.0 (a /17) you would not change the first two octets in your calculations.

10.0.0.1 - 10.0.127.254
10.0.128.1 - 10.0.255.254

so I'm pretty sure you should stop here.

Hi,

Thanks for the reply.

Can anyone confirm this as the info I read was from Techrepublic and it now seems I have conflicting information.

Thanks

MosGuy

control wrote: »

Hi,

Thanks for the reply.

Can anyone confirm this as the info I read was from Techrepublic and it now seems I have conflicting information.

Thanks

The numbers in your original post are correct. 512 subnets with 32,766 hosts. With ranges:

10.0.0.1 - 10.0.127.254
10.0.128.1 - 10.0.255.254
10.1.0.1 - 10.1.127.254
10.1.128.1 - 10.1.255.254
10.2.0.1 - 10.2.127.254
....
Last valid: 10.255.128.1 10.255.255.254

Picker

control wrote: »

Hi,

Thanks for the reply.

Can anyone confirm this as the info I read was from Techrepublic and it now seems I have conflicting information.

Thanks

I would go with whats on Techrepublic. I think you should by looking at the first octet of the IP address which is 10. that tells us its a calss a address and when you look at the subnet mask you have 255.255.128.0 that means this has been subnetted by someone.

you would be right in saying you have 512 subnet and 32,766 hosts.

control

Thanks a lot to both of you...feel better now