ISP assigns a Public IP address for your computer or mobile when you connect. ISP provides you with Public IP Adress
The Internet Assigned Numbers Authority (IANA) organization coordinates through all Regional Internet Registries and ISPs to allocates the IP addresses, Then ISP assigns you a Public IP address
either IPv4 or IPv6 when you connect, which are allocated to them.
ISP assigns you only a Public IP address.
Story: Your router connects through the internet is assigned one public IP by ISP, Then the router assigns a local private IP to each device it connects and manages. So all devices connected
to the router have the same public IP, The router smartly manages with all devices connecting to and fro to the internet.
ICANN coordinating the maintenance and procedures of several databases related to the namespaces and numerical spaces like domain names and IP addresses.
IANA is responsible for the operation of assignment of IP in a hierarchy, ISPs obtain allocations of IP addresses from a local Internet registry (LIR) or National Internet Registry (NIR), or from their appropriate Regional Internet, Which are given by IANA.
| Registry | Region |
|---|---|
| AFRINIC | Africa Region |
| APNIC | Asia/Pacific Region |
| ARIN | Canada, USA, and some Caribbean Islands |
| LACNIC |
Latin America and some Caribbean Islands |
| RIPE NCC |
Europe, the Middle East, and Central Asia |
Bytes: First and last IP of any subnet is reserved, First IP is used as the network number and Last IP is used as broadcast address
Static IP vs Dynamic IP
Static IP is one that is assigned by ISP or a device that never changes even on network reconnection. Usually when assigned by ISP as a static IP would cost a flat fee as it will not return to their IP Pool, Wheres the dynamic IP may not guarantee the same when reconnected.
For web servers, Email servers, and business, having static IP will make things easier as IP need not be frequently remapped in order to connect to the right server or system.
In a local network, DHCP controls the IP assignment for each connected device and avoid clashed between IP
Private IP Ranges
| Class | IP Range | No of IP Addresses |
|---|---|---|
| Class A | 10.0.0.0 - 10.255.255.255 | 16,777,216 |
| Class B | 172.16.0.0 - 172.31.255.255 | 1,048,576 |
| Class C | 192.168.0.0 - 192.168.255.255 | 65,536 |
Note: 4,294,967,296 IPv4 Addresses are there
More Detailed Info Below on IP Addresses
Classless inter-domain routing (CIDR) is a set of Internet protocol (IP) standards that are used to create unique identifiers for networks and individual devices.
Eg. 173.245.48.0/20: This is sample CIDR for Cloudflare IPs, CIDR is represented with a slash followed by a number.
CIDR is just a compact representation of an IP Block, It can be converted to IP Range also.
NAT acts as an agent for local networks and the internet. As said above for a network only one public IP is assigned, Each other device connected in the network will be assigned only local private IP. But each device needs to access the internet and download it independently. But any device to connect to the internet needs Public IP.
To overcome the above problem NAT just maintains the local network mapping with each local Private IP and Public IP. So a packet request from your mobile A will get a response back to Mobile A and not to Mobile B though both have the same Public IP according to the outer world. The only difference is each has its unique private IP within a local network.
Cubepost, Jul 27, 2020
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