What is a MAC address and what is a MAC address

The MAC address is the NIC address.

A MAC (Media Access Control) address is an identifier that identifies a LAN (Local Area Network) node. The physical address of a network card is usually the EPROM (a flash memory chip, usually written by a program) burned into the network card by the network card manufacturer, which stores the addresses of the computer that really identifies the computer that sent the data and the host that received the data when transmitting data.

That is to say, in the physical transmission process at the bottom of the network, the host is identified by the physical address, which is generally unique in the world. For example, the physical address of a well-known Ethernet card is an integer of 48 bits (bits), such as: 44-45-53-54-00-00, which is stored in a machine-readable way into the host interface.

The Ethernet Address Management Authority (IEEE) divides Ethernet addresses, that is, different combinations of 48 bits, into several independent contiguous address groups, and manufacturers who produce Ethernet network cards purchase one of them, and give unique addresses to Ethernet cards one by one during specific production.

Figuratively speaking, the MAC address is like the ID number on our ID card, which is globally unique.

How do I get a native Mac?

For a small number of machines, we can get the MAC address like this: in Windows 98 ME, click "Start" "Run" and enter "WinIPCFG" Enter. You can see the MAC address.

In Windows 2000 XP, click Start Run Enter cmd Enter Enter IPCONFIG ALL Enter. You can see the MAC address.

The computer can be accurately located through the network card address, of course, the MAC address may also be logically copied by certain means, so that two machines can share the same IP address to surf the Internet, and the problem of few IP address resources is solved.

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MAC is the physical address, that is, the actual address of the network card. If you bind an IP address to a MAC address in the local area network, no one else can use the IP.

MAC address (Media Access Control Address), literally translated as ** access control address, also known as LAN address, Ethernet address or physical address, is an address used to confirm the location of devices on the network. Figuratively speaking, a MAC address is like an ID number on an ID card, which is globally unique.

In the OSI model, the MAC address focuses on the second layer of data linking, which transfers one data frame from one node to another node on the same link. If a device has one or more NICs, each NIC needs and will have a unique MAC address.

The MAC address is 48 bits (6 bytes) in length and consists of hexadecimal digits, divided into the first 24 bits and the last 24 bits: the first 24 bits are called the unique identifier of the organization, which is assigned by the IEEE registry to different vendors. The last 24 bits are assigned by the manufacturers themselves and are called extended identifiers.

The last 24 bits of MAC address in NICs produced by the same manufacturer are different.

MAC address refers to the ** access control address, which is an address used to confirm the location of a network device.

The full name of MAC address is Media Access Control, also known as LAN address, Ethernet address or physical address, which is mainly determined by the network card of the computer, and it is fixed and generally not changed. Each host will have a unique MAC address.

The MAC address is 48 bits (6 bytes) in length, usually represented as 12 hexadecimal numbers, separated by colons between each 2 hexadecimal numbers, for example: 00:50:29:5a:8h:1e is a MAC address.

The MAC address is applied at the second layer of the OSI, which is the data link layer. The Data Link Layer protocol enables data to be passed from one node to another node on the same link (via MAC address).

The IP address is 32 bits, consisting of four 8 octets separated by dots, such as an IP address, which is called dot decimal format.

The IP address is applied to the third layer of OSI, which is the network layer. The network layer protocol enables data to be passed from one network to another (ARP finds the MAC address of the intermediate node based on the destination IP address, transmits it through the intermediate node, and finally reaches the destination network).

1. MAC address, literally translated as **access control address, also known as LAN address, MAC address, Ethernet address or physical address It is an address used to confirm the location of network equipment. In the OSI model, the third layer of the network is responsible for the IP address, and the second layer of the data link layer is responsible for the MAC address. If a device has one or more NICs, each NIC needs to have a unique MAC address.

2. The MAC address is also called the physical address and hardware address, which is burned into the EPROM (a flash memory chip, usually erased by the program) when produced by the network equipment manufacturer. Both IP addresses and MAC addresses are represented in binary in computers, with IP addresses being 32-bit and MAC addresses being 48-bit.

Let's put it this way: there is no possibility of running out, MAC address is the address used by the link layer to the network layer, used to identify a host in the same broadcast domain (LAN), a broadcast domain is the range of all interfaces of a switch, out of this range is that the IP address and MAC address have no half-dime relationship, the largest switch I have not seen more than 100 interfaces, but MAC addresses have 2 48, the possibility of conflict is too small. If the network equipment manufacturer can guarantee that the device will not be manufactured with the same MAC address for 10 years, then there is no possibility of conflict at all.

LAN: Several hosts (possibly computers and routers) can be connected to a switch or hub, and when a host wants to send data, a piece of data is formed"MAC address - IP address - destination host port - data"In the form of common Ethernet, the channel you use to send data (such as network cable, wifi) is shared by multiple hosts (there is a little difference when using network cable to connect to the switch, but in essence it is still a shared medium), all hosts will receive the data sent by others (ARP spoofing implementation basis), other hosts will confirm whether the data is sent to themselves through the MAC address, and ordinary terminal hosts (such as mobile phones, computers) will receive this data if they find it their own, otherwise it will be discardedWhen the router receives this data, if there is no path to the destination IP address in its own routing table, it will be discarded, if there is, the MAC address will be stripped and the MAC address of the destination router interface on the next hop network segment will be added, and the next router will be sent to the next router in the same way until it reaches the destination host, so the MAC address will only take effect when the next host is selected, and it will become invalid after reaching the interface of the next host.

Nowadays, we use optical fiber to connect to the Internet network, and the only physical connection between the two hosts is used, and it is no longer a shared media network, but a so-called P2P network, and there is no need for MAC addresses to exist on this network.