Private IP address vs. public IP address

Private IP address is only used within a LAN or an internal network (e.g. home or company network), while public IP address is used for communication over the Internet. If your computer is part of a company network, chances are it is assigned a private IP address and when it connects to the Internet the private IP address is translated to a public IP address by a router which has NAT capability. Private IP address is also known as internal IP address, while public IP address is external IP address. LAN IP address is always a private IP address, while WAN IP address can be a private or public IP address. This article clarifies the difference between LAN IP address and WAN IP address.

OK, in case you are wondering, the table below tells you which IP addresses are allocated for use only in internal networks as private IP addresses.

IP address class private IP address range
  From To
Class A
Class B
Class C

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What is the function of IP address?

IP addresses are used by devices called routers on the Internet to forward messages from one computer to another over the Internet. In comparison to a telephone network, a router acts like a telephone switch (exchange) that connects a caller to the dialed phone number.

When you send a message over the Internet, the message is broken down into small pieces - called packets - where each packet can take its own route. IP addresses information is included in the packet header. Your computer sends each packet along with your computer (i.e. source) IP address and the receiving computer (i.e. destination) IP address. The routers read the source and the destination IP addresses by examining a packet header and forward the packet accordingly.

However, you usually type a web address (e.g. instead of an IP address in your browser's address bar. That's because there are servers on the Internet that store the mapping of web addresses to IP addresses. They are called DNS servers. The DNS servers handle the translation from a web address to an IP address. A DNS server is analogous to a telephone directory that contains a list of telephone numbers and businesses or individuals who own the numbers.

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==>> How many routers do forward my message before arriving at a specific web address?

Your message does not get to the destination address via one router. There are many routers involved in forwarding your message to the destination computer (i.e. in this case, a web server). You can do little investigation by typing tracert ip_address or tracert web_address in Command Prompt. Replace the ip_address or web_address part after tracert with your destination, e.g. This command will trace the routes that take your message to its destination by sending ICMP messages. Some routers have been set not to accept an ICMP message from the Internet therefore you won't get a reply. But since many allow it, by reading the result you would be amazed at how far your message can travel in milliseconds and how many hops it makes to get to its destination.

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How will the website I visit use my IP address?

Your IP address can be used for location targeting that is identifying where you come from and presenting you relevant content tied to your geographic location. That's because IP addresses in bulk are allocated to regions and countries around the world by the IANA in a delegated manner through several Regional Internet Registries. And each ISP obtains IP addresses for its subscribers from Local or National Internet Registry.

Nonetheless, a website you visit can not know who you are, solely from your IP address. Unless you register to the website and gives it your personal information, you will remain anonymous.

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