The proper term for this process is DNS name resolution, and you would say that the DNS server resolves the domain name to the IP address. Whether you’re accessing a Web site or sending e-mail, your computer uses a DNS server to look up the domain name you’re trying to access. Instead, you just connect through a domain name server, also called a DNS server or name server, which manages a massive database that maps domain names to IP addresses. Thanks to DNS, though, you don’t have to keep your own address book of IP addresses. This is similar to dialing a phone number to connect to the person you’re trying to call.
If one DNS server doesn’t know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.Ĭomputers and other network devices on the Internet use an IP address to route your request to the site you’re trying to reach. The DNS system is, in fact, its own network. For example, the domain name might translate to 198.105.232.4. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. The Internet however, is really based on IP addresses. Because domain names are alphabetic, they’re easier to remember. The types of message are:ĭomain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. These are identified by four values in the “operation” field of an arp message. There are four types of arp messages that may be sent by the arp protocol.
The processes are normally implemented as part of the software driver that drives the network interface card. The arp client and server processes operate on all computers using IP over Ethernet. IP operates at the network layer and is not concerned with the link addresses of individual nodes which are to be used.The address resolution protocol (arp) is therefore used to translate between the two types of address. The Ethernet address is a link layer address and is dependent on the interface card which is used.
A computer sends all packets which it creates with its own hardware source link address, and receives all packets which match the same hardware address in the destination field or one (or more) pre-selected broadcast/multicast addresses. This is the normal link source address used by an interface.
Each computer network interface card is allocated a globally unique 6 byte link address when the factory manufactures the card (stored in a PROM). The hardware address is also known as the Medium Access Control (MAC) address, in reference to the standards which define Ethernet. The destination address (all 1’s) may also identify a broadcast packet (to be sent to all connected computers). The address resolution procedure is completed when the client receives a response from the server containing the required address.Īn Ethernet network uses two hardware addresses which identify the source and destination of each frame sent by the Ethernet. The information received by the server allows the server to uniquely identify the network system for which the address was required and therefore to provide the required address. The address is “resolved” using a protocol in which a piece of information is sent by a client process executing on the local computer to a server process executing on a remote computer. The term address resolution refers to the process of finding an address of a computer in a network.
It is used when IPv4 is used over Ethernet. The protocol operates below the network layer as a part of the interface between the OSI network and OSI link layer. The address resolution protocol (arp) is a protocol used by the Internet Protocol (IP), specifically IPv4, to map IP network addresses to the hardware addresses used by a data link protocol.