Dns records and messages - application layer, Computer Networking

DNS Records  and Messages

Two types  of records  are used DNS. The  question records  are used in the question  section of the query and response  messages. The resource  records  are used in the  answer  authoritative  and additional  information sections of the  response  message.

Question Record: A questions records in used by the client  to get  information  from a server. This contains the domain  name.

Resource Record: Each domain  name is  associated  with a  record  called  the resource  record. The server database  consists  or resource  returned by the server to the client.

A resource  records is a quadruple that contains the  following  fields.

Name , Value , Type , TTL

TTL  is the time  to live of  the resource records. It determines  when a resource  should be  removed  from a cache form a  cache. In the example  records given below  we ignore the TTL  field.

The  meaning of  name  and value  depend on  type:

If a DNS  server is authoritative for a  particular host name  then the DNS  server will  contain  a type a record for the  hostname. If a server is not authoritative  for a hostname  then the  server will contain a type NS record for the  domain  that includes the hostname. It  will also  contain  a Type  a record that provides the IP address of the DNS  server in the value field of the NS  records. As an example suppose an edu TLD server is not  authoritative for the host gain cs un mass edu. Then this server will contains  a record for a  domain that includes the host cs mass. Edu. For example  ( umass edu dns unmass. Edu  NS) the du TLD server would  also contain a Type a record which maps the DNS. Server dns  umass.edu to an IP address for example  ( dns umass edu 128.119.111A)

Posted Date: 3/9/2013 4:27:58 AM | Location : United States







Related Discussions:- Dns records and messages - application layer, Assignment Help, Ask Question on Dns records and messages - application layer, Get Answer, Expert's Help, Dns records and messages - application layer Discussions

Write discussion on Dns records and messages - application layer
Your posts are moderated
Related Questions
Question Which elementary logic gate is equivalent to this circuit? Show your working.

Take the maximum packet lifetime, T.  It's stated that T must be big enough to make sure the packet and its ACK have vanished.  Why do we have to have the ACK?

Explain the Forward congestion avoidance process Notifies the user that congestion avoidance process should be initiated where applicable for traffic in the similar direction a

What is meant by Symmentric Multiprocessing (SMP)? It treats all processors as equal. Any processor can do the work of any other processor. Applications are divided into thread

Determine the definition of HDLC HDLC has only one address field. In a LAN, any station may transmit to any other station. The receiving station needs to see its own address in

What is packet filter? Packet filter is a standard router up to with some extra functionality. The extra functionality permits every incoming or outgoing packet to be inspected

Data Alignment Arrays are aligned to templates by the ALIGN directive. The ALIGN directive is used to align elements of different arrays with each other, indicating that they s

Q. Explain Dynamic Domain Name System? DDNS - Dynamic Domain Name System automatically updates the DNS master file - Sent by DHCP to a primary DNS server; secondary se

Define Decoder? A device or program that translates encoded data into its original format (e.g. it decodes the data). The term is often used in reference to MPEG-2 video and so

What Automatic Repeat Request (ARQ)? Error control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaged in tr