What is public ip address range

What is public ip address range:

Public IP Address Range

Class A(Netid.hostid.hostid.hostid) : 1.0.0.0 to 126.0.0.0
Class B(Netid.Netid.hostid.hostid) : 128.0.0.0 to 191.0.0.0
Class C(Netid.Netid.Netid.hostid) : 192.0.0.0 to 223.0.0.0
Class D(Multicast) : 224.0.0.0 to 239.0.0.0
Class E(For Research) : 240.0.0.0 to 255.0.0.0

Based on the wonderful growth of the internet, it soon became evident that the IP address space would quickly become exhausted if the growth continued. To account for this, the IETF looked for ways in which the address space currently obtainable could be extended. A future solution exists in the kind of IP version 6 (or IPv6 for short), which makes use of a much larger 128-bit addressing system. In order to deal with the issue in the shorter term, it was decided that definite address ranges would be deemed "private".

Private IP Address Range:

Class A(/8) : 10.0.0.0 to 10.255.255.255

Class B(/12) : 172.16.0.0 to 172.31.255.255
Class C(/16) : 192.168.0.0 to 192.168.255.255

Note:

/8 = First 8 Bits are used for Network ID
/12 = First 12 Bits are used for Network ID
/16 = First 16 Bits are used for Network ID

The idea behind private ranges of IP addresses is surprisingly simple – certain IP address ranges would be dedicated and limited to use for hosts on private networks. These addresses would no longer be considered valid (or be routable) on the public Internet. Instead, companies could allocate addresses in these ranges as they saw fit, with the address ranges open and available to everyone. Private IP addresses are a practical solution, since companies can use technologies such as Network Address Translation or Proxy servers to connect their private networks to the public Internet. When these technologies are used, a single public IP address can be used to connect an entire organization to the Internet.

As of 2008, IPv6 is generally seen as the only practical long-term solution for IPv4 address exhaustion that is readily available. However, although the predicted IPv4 address exhaustion approaches, most ISPs, software vendors and service providers are only just starting to consider widespread deployment of IPv6.

IPv6 Address Types

Increasing the IP address pool was one of the major forces behind developing IPv6. It uses a 128-bit address, meaning that we have a maximum of 2¹²⁸ addresses available, or 340,282,366,920,938,463,463,374,607,431,768,211,456, or enough to give multiple IP addresses to every grain of sand on the planet. So our friendly old 32-bit IPv4 dotted-quads don't do the job anymore; this new-fangled IPs require eight 16-bit hexadecimal colon-delimited blocks. So not only are they longer, they use numbers and letters. At first glance, those mondo IPv6 addresses look like impenetrable secret code:

 2001:0db8:3c4d:0015:0000:0000:abcd:ef12

Let's look at the different types of IPv6 addressing.

Under IPv4 we have the old familiar unicast, broadcast and multicast addresses. In IPv6 we have unicast, multicast and anycast. With IPv6 the broadcast addresses are not used anymore, because they are replaced with multicast addressing.

IPv6 Unicast

This is similar to the unicast address in IPv4 – a single address identifying a single interface. There are four types of unicast addresses:

• Global unicast addresses, which are conventional, publicly routable address, just like conventional IPv4 publicly routable addresses.
• Link-local addresses are akin to the private, non-routable addresses in IPv4 (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16). They are not meant to be routed, but confined to a single network segment. Link-local addresses mean you can easily throw together a temporary LAN, such as for conferences or meetings, or set up a permanent small LAN the easy way.
• Unique local addresses are also meant for private addressing, with the addition of being unique, so that joining two subnets does not cause address collisions.
• Special addresses are loopback addresses, IPv4-address mapped spaces, and 6-to-4 addresses for crossing from an IPv4 network to an IPv6 network.

Multicast in IPv6 is similar to the old IPv4 broadcast address a packet sent to a multicast address is delivered to every interface in a group. The IPv6 difference is it's targeted instead of annoying every single host on the segment with broadcast blather, only hosts who are members of the multicast group receive the multicast packets.

Anycast address is a single address assigned to multiple nodes. A packet sent to an anycast address is then delivered to the first available node. This is a slick way to provide both load-balancing and automatic failover.

Address Dissection

Let's take another look at our example IPv6 address:

2001:0db8:3c4d:0015:0000:0000:abcd:ef12

______________|____|___________________

global prefix subnet  Interface ID

The prefix identifies it as a global unicast address. It has three parts: the network identifier, the subnet, and the interface identifier.

IPv6 addresses must total 128 bits. IPv4 addresses are represented like this:

0000:0000:0000:0000:0000:0000:192.168.1.25

Eight blocks of 16 bits each are required in an IPv6 address. The IPv4 address occupies 32 bits, so that is why there are only seven colon-delimited blocks.

The local host address is 0000:0000:0000:0000:0000:0000:0000:0001.

Naturally we want shortcuts, because these are long and all those zeroes are just dumb-looking. Leading zeroes can be omitted, and contiguous blocks of zeroes can be omitted entirely, so we end up with these:

2001:0db8:3c4d:0015:0:0:abcd:ef12

   2001:0db8:3c4d:0015::abcd:ef12

::192.168.1.25

::1

ipv6calc is invaluable for checking your work. Suppose you're not sure if your compressed notation is correct. ipv6calc displays the uncompressed notation:

$ ipv6calc --in ipv6addr --out ipv6addr --printuncompressed ::1

0:0:0:0:0:0:0:1

$ ipv6calc --in ipv6addr --out ipv6addr --printfulluncompressed 2001:0db8:3c4d:0015::abcd:ef12

2001:0db8:3c4d:0015:0000:0000:abcd:ef12