Notes on Domain Name Servers by hcj


									Notes on Domain Name Servers
DNS are hierarchical. The structure of a domain’s servers is up to the manager of the domain. Each server must know about all of the servers below it in the hierarchy. A server must also know a root server to ask when it doesn’t know the name.

There are two basic types of requests that can be sent to a DNS.


A recursive request will respond with the answer or an error message if the host is not known. This is the type of request made by a client when the user program executes a gethostbyname function. An Interative request will respond with the answer or the name of a DNS that may be able to answer the question. This type of request is usually used between Domain Name Servers.

A server has different types of entries:
  

Address entries relate a name to address. Abbreviations - host names without the domain name. Mail eXchange entries relate a mail address to IP address. This is why you can send email to a name that you can’t use for the web or ftp, such as

Further information on Domain Name Servers can be found at

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