1 / 19

Computer Communication & Networks

Computer Communication & Networks. Lecture 26 Application Layer: Domain Name System http://web.uettaxila.edu.pk/CMS/coeCCNbsSp09/index.asp. Waleed Ejaz waleed.ejaz@uettaxila.edu.pk. Application Layer. Application Layer Topics to Cover. DNS. Remote Logging. Electronic Mail.

dalicia
Télécharger la présentation

Computer Communication & Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Computer Communication & Networks Lecture 26 Application Layer: Domain Name System http://web.uettaxila.edu.pk/CMS/coeCCNbsSp09/index.asp Waleed Ejaz waleed.ejaz@uettaxila.edu.pk

  2. Application Layer

  3. Application Layer Topics to Cover DNS Remote Logging Electronic Mail File Transfer

  4. Name Space • To be unambiguous, the names assigned to machines must be carefully selected from a name space with complete control over the binding between the names and IP addresses.

  5. Domain Name Space • To have a hierarchical name space, a domain name space was designed. In this design the names are defined in an inverted-tree structure with the root at the top. The tree can have only 128 levels: level 0 (root) to level 127.

  6. Domain name space

  7. Domain names and labels

  8. Domains

  9. Distribution of Name Space • The information contained in the domain name space must be stored. However, it is very inefficient and also unreliable to have just one computer store such a huge amount of information. In this section, we discuss the distribution of the domain name space.

  10. Hierarchy of Name Servers

  11. DNS in the Internet • DNS is a protocol that can be used in different platforms. In the Internet, the domain name space (tree) is divided into three different sections: generic domains, country domains, and the inverse domain.

  12. DNS IN THE INTERNET

  13. Generic Domains

  14. Generic domain labels

  15. Country domains

  16. Resolution • Mapping a name to an address or an address to a name is called name-address resolution.

  17. Recursive resolution

  18. Iterative Resolution

  19. once (any) name server learns mapping, it caches mapping cache entries timeout (disappear) after some time DNS: caching and updating records

More Related