Presented By:   Diwaker pantME (ECE) Regular
   DNS- Definition   Name Space    ◦ Flat Name Space    ◦ Hierarchical Name Space   Domain Name Space    ◦ FULLY QUALIF...
   To identify an entity, TCP/IP uses IP addresses which    uniquely identifies connection of host to internet.   We pre...
   When internet was small, mapping was done using    HOST FILE which was stored on every host.   Host file had only two...
   The process of mapping a unique name with the unique    IP address.   FLAT NAME SPACE –    A name is assigned to an ...
   HIERARCHICAL NAME SPACE-    Each name is made of several parts.   The first part can define the nature of organizati...
   To have a hierarchical name space, a DOMAIN NAME    SPACE was designed.   In this design the names are defined in an ...
 Label is a string with a max. of 63 characters. The root label is a null string. Siblings have different labels to mai...
   Each node in the tree has a domain name.   Full domain name is sequence of labels separated by    dots(.)   Domain n...
DNS   By Diwaker Pant   October 9, 2012   10
    FULLY QUALIFIED DOMAIN NAME(FQDN)     It contains the full name of host.     A label is terminated by a null string...
 Domain    is a sub       tree of domain       name space.    Each    domain can       be divided into       sub domains...
DNS   By Diwaker Pant   October 9, 2012   13
    Region over which server      has the responsibility and      authority.     Zone is a part of entire      tree.   ...
   ROOT SERVER-It is a server whose zone consist of    whole tree. These servers are distributed all around the    world....
 DNS is a protocol can be used in different platforms. In the internet, DNS tree is divided into three different section...
   It contains registered hosts according to generic behaviors.October 9, 2012                  DNS   By Diwaker Pant    ...
Label                                  Description          com     Commercial organizations          edu     Educational ...
Label                                Description aero             Airlines and aerospace companies  biz             Busine...
Two characters country abbreviations.                     DNS   By Diwaker Pant   October 9, 2012   20
    Use to map an address to a      name.     When a server received a      request from a client to do a      task.   ...
   Mapping a name to an address or an address to a name is    called name –address resolution.   RESOLVER-It access the ...
   MAPPING ADDRESS TO NAMES.   Resolver sends IP address to the server to be mapped    to domain name.   This is called...
RECURSIVE RESOLUTIONOctober 9, 2012     DNS   By Diwaker Pant   24
   ITERATIVE RESOLUTION                           DNS   By Diwaker Pant   October 9, 2012   25
   CACHING   When a server asks for mapping from another server and    receive the response, it stores the information a...
 Query and response                       DNS   By Diwaker Pant   October 9, 2012   27
DNS   By Diwaker Pant   October 9, 2012   28
   In DNS , when there is a change , such as adding a new    host, removing a host or changing an IP address,    change m...
   DNS can use either UDP or TCP.   PORT NO. 53 is used by servers.   If size of response message is more than 512 byte...
   This is done through a registrar, a commercial entity    accredited by ICANN (Internet corporation for    assigned nam...
 The domain name system is a client /server application  that identifies each host on the internet with a unique  friendl...
   Behrouz A. Forouzan - Data Communication and    Networking (3rd ,4th edition)   Andrew S. Tanenbaum - Computer Networ...
DNS   By Diwaker Pant   October 9, 2012   34
The client (resolver) can ask for the answer from a name server,generally closet DN server.If the server is the authority ...
If the clients does not ask for the recursive answer, the mapping canbe done iteratively.If the server is an authority for...
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Domain name system

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  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 rd edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition) The client (resolver) can ask for the answer from a name server, generally closet DN server. If the server is the authority for the domain name it will responds back with the full answer after checking its database, but if the closet server is not the authority then it will pass query to next closet server generally parent. Then this server will again check its database and responds back with answer if it is authority, otherwise it will pass the query to next server… This process will repeats until the authoritative server gives final answer. When the query is finally resolved. The response travels back to requesting client.
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Behrouz A. Forouzan - Data Communication and Networking (3 rd ,4 th edition)
  • Domain name system

    1. 1. Presented By: Diwaker pantME (ECE) Regular
    2. 2.  DNS- Definition Name Space ◦ Flat Name Space ◦ Hierarchical Name Space Domain Name Space ◦ FULLY QUALIFIED DOMAIN NAME(FQDN) ◦ PARTIALLY QUALIFIED DOMAIN NAME(PQDN) Distribution of Name Space ◦ Hierarchy of Name servers ◦ Zone and Domains ◦ Root, Primary and Secondary Servers DNS in Internet ◦ Generic , Country and Inverse Domain Resolution DNS messages DNS By Diwaker Pant October 9, 2012 2
    3. 3.  To identify an entity, TCP/IP uses IP addresses which uniquely identifies connection of host to internet. We prefer to use names instead of numeric addresses . So we need a system that can map a name to a numeric address and vice versa. This is called DOMAIN NAME SYSTEM DNS By Diwaker Pant October 9, 2012 3
    4. 4.  When internet was small, mapping was done using HOST FILE which was stored on every host. Host file had only two columns: name and address. But now a days whole information is divided into smaller parts and each part is stored in different computer. This is called DNS. DNS By Diwaker Pant October 9, 2012 4
    5. 5.  The process of mapping a unique name with the unique IP address. FLAT NAME SPACE – A name is assigned to an address and name is a sequence of characters without structure. It can not be used in large system such as Internet. DNS By Diwaker Pant October 9, 2012 5
    6. 6.  HIERARCHICAL NAME SPACE- Each name is made of several parts. The first part can define the nature of organization. Second part can define the name and third can define the departments in organization. For exampleo Smart.pu.eduo Smart.nitttr.eduo smart.unix.com DNS By Diwaker Pant October 9, 2012 6
    7. 7.  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 top. The tree can have only 128 levels i.e. level 0(root) to level 127. Tree consists of nodes and each node has a LABEL. DNS By Diwaker Pant October 9, 2012 7
    8. 8.  Label is a string with a max. of 63 characters. The root label is a null string. Siblings have different labels to maintain uniqueness. DNS By Diwaker Pant October 9, 2012 8
    9. 9.  Each node in the tree has a domain name. Full domain name is sequence of labels separated by dots(.) Domain name is read from node up to root. Always ends in a null label i.e. last character is a dot. DNS By Diwaker Pant October 9, 2012 9
    10. 10. DNS By Diwaker Pant October 9, 2012 10
    11. 11.  FULLY QUALIFIED DOMAIN NAME(FQDN)  It contains the full name of host.  A label is terminated by a null string.  PARTIALLY QUALIFIED DOMAIN NAME(PQDN)  It starts from a node but doesn’t reaches root.  A label is not terminated by null string.October 9, 2012 DNS By Diwaker Pant 11
    12. 12.  Domain is a sub tree of domain name space.  Each domain can be divided into sub domains.October 9, 2012 DNS By Diwaker Pant 12
    13. 13. DNS By Diwaker Pant October 9, 2012 13
    14. 14.  Region over which server has the responsibility and authority.  Zone is a part of entire tree.  Server can divide domain into smaller domains.October 9, 2012 DNS By Diwaker Pant 14
    15. 15.  ROOT SERVER-It is a server whose zone consist of whole tree. These servers are distributed all around the world. PRIMARY SERVER- A primary server loads all information from the local disk file. SECONDARY SERVER- It transfer the complete information from the primary server and it is called Zone transfer. DNS By Diwaker Pant October 9, 2012 15
    16. 16.  DNS is a protocol can be used in different platforms. In the internet, DNS tree is divided into three different sections DNS By Diwaker Pant October 9, 2012 16
    17. 17.  It contains registered hosts according to generic behaviors.October 9, 2012 DNS By Diwaker Pant 17
    18. 18. Label Description com Commercial organizations edu Educational institutions gov Government institutions int International organizations mil Military groups net Network support centers org Nonprofit organizationsOctober 9, 2012 DNS By Diwaker Pant 18
    19. 19. Label Description aero Airlines and aerospace companies biz Businesses or firms (similar to com) coop Cooperative business organizations info Information service providersmuseum Museums and other nonprofit organizations name Personal names (individuals) pro Professional individual organizationsOctober 9, 2012 DNS By Diwaker Pant 19
    20. 20. Two characters country abbreviations. DNS By Diwaker Pant October 9, 2012 20
    21. 21.  Use to map an address to a name.  When a server received a request from a client to do a task.  Inverse or pointer (PTR) query.  121.45.34.132.in-addr.arpaOctober 9, 2012 DNS By Diwaker Pant 21
    22. 22.  Mapping a name to an address or an address to a name is called name –address resolution. RESOLVER-It access the closest DNS server with a mapping request. If the server has the information, it satisfies the resolver ; otherwise refers the resolver to other servers or asks the other servers to provide the information. MAPPING NAMES TO ADDRESSES- Resolver gives domain name to the server and ask for address. It uses country and generic domain to find the mapping. DNS By Diwaker Pant October 9, 2012 22
    23. 23.  MAPPING ADDRESS TO NAMES. Resolver sends IP address to the server to be mapped to domain name. This is called PTR or Inverse query. Server uses inverse domain.IP address -121.45.34.132Domain name-132.34.45.121.in-addr.arpa. DNS By Diwaker Pant October 9, 2012 23
    24. 24. RECURSIVE RESOLUTIONOctober 9, 2012 DNS By Diwaker Pant 24
    25. 25.  ITERATIVE RESOLUTION DNS By Diwaker Pant October 9, 2012 25
    26. 26.  CACHING When a server asks for mapping from another server and receive the response, it stores the information an its cache memory before sending it to the clients. If the same or other client ask for the same mapping, it can check its cache memory and resolve the problem. But this type of response is always marked as unauthoritative. DNS By Diwaker Pant October 9, 2012 26
    27. 27.  Query and response DNS By Diwaker Pant October 9, 2012 27
    28. 28. DNS By Diwaker Pant October 9, 2012 28
    29. 29.  In DNS , when there is a change , such as adding a new host, removing a host or changing an IP address, change must be made to the DNS master file. Manual updating is not possible due to size of Internet. It is use to update DNS master file automatically. Information in both primary and secondary servers is changed. DNS By Diwaker Pant October 9, 2012 29
    30. 30.  DNS can use either UDP or TCP. PORT NO. 53 is used by servers. If size of response message is more than 512 bytes, TCP connection is used, otherwise UDP is used. How are the new domains added to the server. DNS By Diwaker Pant October 9, 2012 30
    31. 31.  This is done through a registrar, a commercial entity accredited by ICANN (Internet corporation for assigned name and numbers). Name is added to the DNS database after verification by Registrar for uniqueness of the name. A fee is charged. DNS By Diwaker Pant October 9, 2012 31
    32. 32.  The domain name system is a client /server application that identifies each host on the internet with a unique friendly name. Its structure is an inverted hierarchical tree structure. Each node in the tree has a domain name. Generic domain , Country domain, Inverse domain. DDNS automatically updates the DNS master. DNS use the service UDP for message of less than 512 bytes .otherwise, TCP is used. DNS By Diwaker Pant October 9, 2012 32
    33. 33.  Behrouz A. Forouzan - Data Communication and Networking (3rd ,4th edition) Andrew S. Tanenbaum - Computer Networks (4th edition) DNS By Diwaker Pant October 9, 2012 33
    34. 34. DNS By Diwaker Pant October 9, 2012 34
    35. 35. The client (resolver) can ask for the answer from a name server,generally closet DN server.If the server is the authority for the domain name it will respondsback with the full answer after checking its database, but if the closetserver is not the authority then it will pass query to next closet servergenerally parent.Then this server will again check its database and responds back withanswer if it is authority, otherwise it will pass the query to nextserver…This process will repeats until the authoritative server gives finalanswer.When the query is finally resolved. The response travels back torequesting client. DNS By Diwaker Pant October 9, 2012 35
    36. 36. If the clients does not ask for the recursive answer, the mapping canbe done iteratively.If the server is an authority for the name, it sends the answer.If it is not then it returns (to the clients) the IP add of the server that itthinks can resolve the problem.The client is responsible for repeating the query to new server.If this new server can resolve the query then it will responds backwith the Final IP address as an answer otherwise it returns the IPaddress of the new server.This process is called Iterative because The client repeats the query tomultiple servers. DNS By Diwaker Pant October 9, 2012 36

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