DNS Configuration


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DNS Configuration

  2. 2. CONTENTS:  Overview  History  DNS-Name Space & Working  Example of DNS Name Space  DNS-Name Server  DNS-Zone  DNS-Configuration
  3. 3. DNS-Overview  Domain Name System (DNS) is a database system that translates a computer's fully qualified domain name into an IP address.  For example Domain name www.amazon.com corresponding to IP address (  DNS serves as an electronic telephone book for a computer network.
  4. 4. HISTORY OF DNS  In 1967, DNS did not exist.  in 1971, Peggy Karp conceived of “host mnemonics” (RFC 226) and develop “HOSTS.txt”  The first version of this file was distributed in 1972.  The Domain Name System was conceived in RFC 799 in 1981 Written by Dr. David Mills.  In 1987, the publication of RFC 1034 and RFC 1035 updated the DNS specification.
  5. 5. DNS –Name Space & Working  The namespace refers to the hierarchical layout of DNS names  the DNS namespace is laid out in an inverted tree.  At the top of the DNS namespace is the "Root" defined by null character  The root is not normally explicitly specified in user applications but when specified is denoted by a trailing period(www.vtc.com)
  6. 6. DNS –Name Space & Working  Below the root in the DNS namespace, are the top level domains or TLDs.  These TLDS are maintained by the Internet corporation for assigned names and numbers, or ICAN, for Internet use  On a private network you can use any TLD you want but it is bad practice in case you ever connect your network to the internet.
  7. 7. DNS –Name Space & Working  The remainder of the namespace is open for use  You can register domain names beneath several of the TLDs
  8. 8. An Example of Name-Space
  9. 9. DNS-Name Server  A Server which handles DNS-Queries called “Name-Server”.  This server hold a list of all the IP addresses within its network and a cache of IP addresses.  When your computer requests an IP address, one of three things happens.
  10. 10. DNS-Name Server  If the requested IP address is registered locally.  If the requested IP address is not registered locally ,but someone within your organization has recently requested the same IP address.  If the requested IP address is not registered locally, and you are the first person to request information about this system in a certain period of time.
  11. 11. DNS ZONES  Every domain name, which is a part of the DNS system, has several DNS settings, also known as DNS records. In order for these DNS records to be kept in order, the DNS zone was created.  Their are 2 types of zones: 1) A forward lookup zone 2) A reverse lookup zone
  12. 12. DNS ZONES  A forward lookup zone is a DNS zone in which hostname to IP address relations are stored. When a computer requests the IP address of a specific hostname, the forward lookup zone is queried and the result is returned.  A reverse lookup zone does just the opposite. When a computer requests the hostname of an IP address, the reverse lookup zone is queried and the result is returned.
  13. 13. STEPS It involves following steps:-  sudo su  nano /etc/network/interfaces – for static IP.  /etc/init.d/networking restart  ifconfig  apt-get install bind9  nano /etc/bind/named.conf.local  nano /etc/bind/db.up.omg (forward lookup zone)  nano /etc/bind/db.192 (reverse lookup zone)  nano /etc/resolv.conf  /etc/init.d/bind9 restart  nslookup sgsits.up.omg & nslookup
  14. 14. Step 1 : nano /etc/network/interfaces – for static IP
  15. 15. Step 2 : /etc/init.d/networking restart
  16. 16. Step 3 : ifconfig - Our DNS Server has now a static IP
  17. 17. Bind9  BIND (Berkeley Internet Name Domain) is an implementation of the DNS protocols and provides an openly redistributable reference implementation of the major components of the Domain Name System.  BIND9 is latest version of BIND architecture.  features of BIND9 : are DNS Security, IPv6,DNS Protocol Enhancements, Views, Multiprocessor Support, and an Improved Portability Architecture.
  18. 18. Step 4 : apt-get install bind9
  19. 19. Step 5 : nano /etc/bind/named.conf.locals
  20. 20. Step 6: nano /etc/bind/db.up.omg
  21. 21.  A(Address):points our domain to an ip address.  AAAA: same as A record.  CNAME(Canonical name): this record points our sub-domain to another domain name  MX(Mail exchanger): MX records control where our emails are received. DNS ZONE RECORDS
  22. 22.  PTR(Pointer): defines what name will be called when an IP address is looked up.  TXT: The TXT records are custom records which contain machine-readable data.  NS: identify the names of the DNS servers. DNS ZONE RECORDS
  23. 23. Step 6 : nano /etc/bind/db.up.omg
  24. 24. Step 7 : nano /etc/bind/db.192
  25. 25. Step 8 : nano /etc/resolv.conf
  26. 26. Step 9 : /etc/init.d/bind9 restart
  27. 27. Step 11 : nslookup sgsits.up.omg & nslookup