Domain Name System Lecture Notes

Domain name system study notes a a.

Domain name system lecture notes. Structure of dns names. The ohio state university raj jain 24 15 name resolution cont each computer has a name resolver routine e g gethostbyname in unix each resolver knows the name of a local dns server resolver sends a dns request to the server dns server either gives the answer forwards the request to another server or gives a referral referral next server to whom request should be sent. On the internet before the implementation of dns the use of names to locate resources on tcp ip networks was supported by a file called hosts. Browser asks your isp name server for the domain s ip address.

Each name consists of a sequence of alphanumeric components separated by periods examples. The isp name server then sends the ip address back to the browser. The domain name system dns defined in rfcs 1034 and 1035 is used on the internet to provide a standard naming convention for locating ip based computers. If your isp name server doesn t know it then asks the root name server where to find the authoratative name server for the domain.

A the domain name system dns is a client server application that identifies each host on the internet with a unique user friendly name. First names are transcribed. Because host names are frequently repeated or very similar in dns responses a compression mechanism is used. If one of the length numbers is on the binary form 11 0xc0 the 6 lsb and the next byte are used as an offset pointer into the packet.