Reserved IP addresses and Special IP addresses

The reserved IP address and the Assigned reserved IP address are all managed by an organization named IANA (Internet Assigned Numbers Authority. IP addresses can be divided into public addresses and private addresses based on their purposes and security levels. Public addresses are used in the Internet and can be accessed freely on the Internet. Private addresses can only be used in internal networks and can communicate with the Internet only through proxy servers. To connect an organization network to the Internet, you must apply for a public IP address. However, considering the special situations such as network security and internal experiments, three private IP addresses are reserved for the IP addresses. The IP address ranges from 10.0.0.0 to 10.0.0.0 ~ 10.20.255.2551 www.2cto.com Class B network 172.16.0.0 ~ 172.31.255.25516c class network 192.168.0.0 ~ 192.168.255.255255 the network with the reserved address can only communicate internally, but cannot communicate with other networks. Because the reserved addresses in the Network may also be used by other networks, if the network is connected, the problem may occur because the address is not unique when looking for a route. However, these networks that use reserved addresses can interconnect with external networks by translating the reserved addresses in the network into public addresses. This is also an important way to ensure network security. The reserved IP address segment is not used on the Internet. Therefore, when a router connected to the WAN processes the reserved IP address, it only discards the packet and does not route it to the WAN, in this way, the data generated by the reserved IP address is isolated within the LAN. If the number of computers in the LAN is less than 254, you can select the IP address range in the C-type IP address segment, for example, from "192.168.1.1" to "192.168.1. 254 ". A special IP address is like 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 used 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 classifications. However, in the total number of approximately more than 4 billion available IP addresses, do you know some common URLs with special meanings below? Let's take a look: www.2cto.com 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. Broadcast bandwidth limit 255 limits 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.
4. 224.0.0.1 multicast address. Pay attention to the difference between it and broadcast. 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. Www.2cto.com 5, 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, it 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, 172.16.x.x ~ 172.31.x.x, 192.168.x.x private addresses, these addresses are widely used in internal networks of enterprises. 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.