What is the private network for Class A IP address?

Is 172 a private IP range?

From what I understood 172.

16.0 through 172.31.255 is a private IP range. So, why would I be able to use 172.30.101.1 as an IP address outside of my LAN?
I realize that any number in the range (from 0 to 127) will work on my public WAN router but not inside my LAN because it would be using the same internal IP. Is this correct? Thanks.

Yes, and so you have a gateway IP of 172.100.1 by putting the following rules in a firewall configuration :

For incoming traffic, have a subnet filter which allows all outbound. Traffic on an INADDRANY address (0.0) to pass.

For incoming traffic, in addition to the subnet filter, use an ACL to block everything not part of 172.0/12 except itself (172.0) This means
Everything not inside the 172.0/12 address range goes to your NAT device which has 172.1 for the NAT device IP address.

Is 10 a private IP range?

Is 10.

0/8 a private IP range? 0/8 is indeed a private IP range. The first three octets of a private IP address are used to denote the type of network. The 4th octet is the subnet mask and the final two octets are the host identifier. A private IP range always uses a netmask of 255.0 or 255.128. These netmasks are not allowed in public ranges, but they are allowed for use within private networks.

How much data is stored in the 10.0/8 range? There is a lot of information in that range. If the end-hosts were able to connect to all other hosts using that range, they would have a total of 256 addresses available to them. However, the typical host address space is 128 addresses, so a lot of that is wasted space.

What about the 172.16.0/12 range?

0/12 is the most common private address range used by ISPs. This range is an example of a Private Address Space with a subnet mask of /12. There are two main reasons that a subnet mask of /12 is used.

1) You have an address range of 10.0/8 and your ISP's address space ends at 172.0/12, you can easily share the same address space as your ISP.

2) The subnet mask of /12 creates a CIDR notation of 172. This makes it easier to remember and enter the address when doing routing and IP addressing.

The following example shows a Private Address Space with a subnet mask of /12.0/12 is not the only way to create a Private Address Space. There are actually many different ways that a subnet mask of /12 can be used. To see all the different ways that you can create a Private Address Space, see the subnet calculator page on the IP Address Space page.

What about the 192.168.0/16 range?

The 192.0/16 range is very similar to the 172.

What is the private IP address range of Class A?

I need to know the private IP address range of Class A, if possible.

The reason is that I need it to be a Class A in an IP address block where Class B is being reserved. There will be a DHCP server in the network and it will give out addresses based on the "Network/LAN subnet mask". We want to use the block of IP addresses that the DHCP server gives out. This would be the Class A range.

The private address space for IPv4 class A networks is 192.168.0/16 (and the same, minus /8, for IPv6).

In case you don't have a native or compatible router, these IP addresses will have no impact on how your LAN/WAN interfaces behave; as such, these IP addresses will be completely useless to your LAN/WAN configuration. As you already said, a DHCP server will return all of those addresses, and as a result, any router or other device connected to that LAN/WAN will get its assigned IP addresses, thus making those devices unusable for your purposes. As @juharr already pointed out in his answer, the addresses in the private address space are of absolutely no relevance to your network; they can simply be disregarded as being completely pointless and unnecessary. They will of course be assigned by your DHCP server for configuration purposes, though - they do have use after all. But that isn't a requirement for being a Class A network address. You can certainly configure your interface in such a way that all addresses in the subnet defined by the Netmask will be used (which includes all addresses in the subnet), even though you'll have no idea about what they actually are; it's not even a common or generally accepted practice, though. What actually matters is what your router will do with the packets, not that it tries to determine whether they were destined for your network or not.

If the router you're configuring has a NAT router set up, it'll still work fine, since the router will receive an address from the pool that is outside the range used by the internal subnet. If the NAT router you're configuring receives its address from the pool, it might do NAT. It doesn't care if it's a "private" address or a public one.