Definition of DNS Lookup
DNS stands for the Domain Name System. A DNS lookup is a request from a client computer to a name server that translates an Internet domain name into an IP address. The request can be a recursive request or an iterative request.
Other People Are Reading
-
The Resolver on the Local Host.
-
Every computer that uses the Internet has a resolver program. Any program on the computer that needs to translate a name into an IP address will request the translation from the resolver. If the resolver cannot find the name in local files, it will initiate a DNS request to a name server.
A Recursive DNS Request.
-
A DNS request is a packet that is sent from a computer's resolver program to a name server on the Internet. The computer must be pre-programmed with the IP address of a name server. The name server will return the IP address corresponding to the name. This is called a recursive request.
-
Iterative Lookup
-
If the DNS server does not have the name cached locally, it will request the address from a higher level server. Higher level servers often do not allow recursive requests. They resolve only one level of the name. For example, a request to a top level server for the name www.thehostingservice.com will return the address of a ".com" server. The next request for www.thehostingservice.com made to the ".com" server would return the address "thehostingservice.com." The final request would be made to the name server for "thehostingservice.com." It would return the IP address of www.thehostingservice.com. This is called an iterative request.
-
References
- Photo Credit name 3d sign image by onlinebewerbung.de from Fotolia.com
