how to figure out new subnet mask for 2,000 subnet network.?

For 2000 subnets you need 11 bits which will give you 2048 subnets with 32 addresses each (30 hosts). The subnet mask will be 255.255.255.224, a /27 address.

The network address can be ignored, so the first 2 octets is irrelevent.

11111111.111 = 2047 leaving 00000 for addresses in each subnet

I'm assuming you know some binary, if not you can google tutorials.

First off, you need to find out how many bits you need to reach the number 2,000. 1 bit can give you 2 numbers, 2 can give 4, 3 can give 8, and so on. 2^(number of bits) = largest possible number.

You can keep going on this way, but I'll just tell you that 2^10 = 1024, then 2^11 = 2048, which gives us the 2,000 we need. So we need 11 bits in our subnet mask.

To make the mask itself, we need to look at the mask in terms of binary. The 255.255.0.0 would be represented as 11111111.11111111.00000000.00000000 since 11111111 = 255. Currently, we can see that there are 16 0's on the end, but we only need 11.

So, we want 11111111.11111111.11111000.00000000. You can plug this in online, or do it by hand, but it works out to 255.255.224.0, your new subnet mask.

Feel free to comment if you have more questions.

do you mean hosts? for hosts, you need to borrow 11 bits which will give you 2048 hosts -2 = 2046 hosts.. so your subnet mask will be 255.255.248.0.... its simple multiply 2 to the 11th power which will give you 2048...same procedure with subnets but instead of borrowing bits from your right of the binary's, you go from the left.

for 2048 subnets it would be a /27

Use a subnet calculator