do the ISP's tell you how many internal IP addresses you can have?

[Churla27]

Do ISP's make that decision or is it up to the admins? Could you use class A IP addresses if you wanted to internally? How does that work? Any input works. Thanks.

 

[~Darkseeker~]

How you set up your internal network is up to you. Your ISP provide the line and the router's public IP - and that's their point of demarcation.

If you set up your internal network in class A (10.x.y.z) you can have exponentially more hosts (16,777,216 or 2^24) because you sacrifice subnets for host bits. Class C network addressing limits you to 254 hosts per subnet, but gives a higher number of subnets with 254 hosts per subnet. Your ISP can't control how you set up your network internally, unless it specifically says so in your service agreement.

 

[Churla27]

OK cool. I was always wondering how it worked. Thanks!

 

[root]

you can also supernet class C subnets if you need more than 256 addresses.