Introduction to Special IP addresses

Just as each of us has an ID card number, each computer on the Network (more specifically, the network interface of each device) has an IP address to identify itself. We may all know that these addresses are composed of four bytes, expressed in dotted decimal notation and Their A, B, and C categories. However, in the total number of around more than 4 billion available IP addresses, do you know some common URLs with special meanings below? Let's take a look:

I. 0.0.0.0

Strictly speaking, 0.0.0.0 is no longer a real IP address. It represents a set of unknown hosts and destination networks. The "unclear" here means that no specific entries in the local route table indicate how to arrive. For the local machine, it is a "Shelter", and all the "Three none" personnel that do not know will be sent in. If you set the default gateway in the network settings, the Windows system will automatically generate a default route with the destination address 0.0.0.0.

Ii. 255.255.255.255

Restrict the broadcast address. For the local machine, this address refers to all hosts in the same broadcast domain in this segment. If translated into human language, it should be like this: "Everyone in this room has noticed it !" This address cannot be forwarded by the router.

Iii. 127.0.0.1

Local Address, mainly used for testing. In Chinese, it is "Myself ". In Windows, this address has an alias "localhost ". Addressing such an address cannot send it to network interfaces. Unless an error occurs, data packets with the target address 127.0.0.1 should never appear on the transmission media.

Iv. 224.0.0.1

Pay attention to the differences between multicast addresses and broadcasts. From 224.0.0.0 to 239.255.255.255. 224.0.0.1 refers to all hosts and 224.0.0.2 refers to all routers. Such an address is mostly used for some specific programs and multimedia programs. If your host has enabled the IRDP (Internet route Discovery protocol, use the multicast function) function, your host routing table should have such a route.

V. 169.254.x.x

If your host uses the DHCP function to automatically obtain an IP address, when your DHCP server fails, or the response time is too long and exceeds the time specified by the system, the wingdows system will assign you such an address. If you find that your host IP address is such an address, unfortunately, your network cannot run normally.

6. 10. x and 172.16. X. X ~ 172.31. X. X, 192.168. X. X

Private addresses, which are widely used in enterprise internal networks. Some broadband routers often use 192.168.1.1 as the default address. The private network may use random IP addresses because it is not interconnected with external networks. This address is reserved for use to avoid address confusion when accessing the public network in the future. When a private network using a private address accesses the internet, you must use address translation (NAT) to translate the private address into a public legal address. This type of address cannot appear on the Internet.

A host on a network can receive three valid destination network addresses: The local IP address, broadcast address, and multicast address.