Need help with a subnetting question

Wisco

I came across the following practice question and don't recall ever seeing one worded like this:

ICANN assigns you the address 221.100.200.0. What is the maximum number of networks achievable by subnetting? What would the subnet mask be?

The answers I came up with are 64 subnets with subnet mask of 255.255.255.252. Is this correct?

mikeybinec

This is a Class C address so your default subnet mask is a /24 or 255.255.255.0.. Using those rules, you are correct

martell1000

yes this is correct

a /24 can have 64 /30s in it

Elijah09

Can someone explain how they got the answers.
Like for example show the work. I would appreciate it. Thanks.

skittledmonkey

Elijah09 wrote: »

Can someone explain how they got the answers.
Like for example show the work. I would appreciate it. Thanks.

I second that - Just after I think I can solve all the subnetting questions, somebody comes along and spoils my fun

Jon_Cisco

221.100.200.0 starting address

221.x.x.x is a class C network falling between 192.x.x.x and 223.x.x.x

The default mask for class C is 255.255.255.0 which allows you to use the last octet for 254 hosts.

You are asked to subnet the host bits in the last octet to produce as many subnets as possible.

smallest subnet requires 2 bits for hosts which allows 4 numbers. Network - host - host - broadcast

This leaves 6 bits to create subnets with. 2 to the power of 6 = 64 subnets

There are lots of ways to do this in your head but this should give you an idea of where the numbers are coming from.

Good Luck

maharaliel

The answer is true. Since 221.100.200.0 is a class c, we can't borrow more that 6 bits from host to bits to network bits. And 6 to power 2 = 64.

skittledmonkey

Jon_Cisco wrote: »

221.100.200.0 starting address

221.x.x.x is a class C network falling between 192.x.x.x and 223.x.x.x

The default mask for class C is 255.255.255.0 which allows you to use the last octet for 254 hosts.

You are asked to subnet the host bits in the last octet to produce as many subnets as possible.

smallest subnet requires 2 bits for hosts which allows 4 numbers. Network - host - host - broadcast

This leaves 6 bits to create subnets with. 2 to the power of 6 = 64 subnets

There are lots of ways to do this in your head but this should give you an idea of where the numbers are coming from.

Good Luck

Clearly explained. Thanks a lot.

Elijah09

I am still a bit confused. But I can see where you got the numbers and understand how you got them.
I guess I need to review the subnetting chapter again. Thanks for the help.