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  • 1. Jainul 1 13-FEB-2014 Thursday Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux Topic: Domain Name Server (Introduction, Installation, Configure DNS)
  • 2. Jainul 2 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. The Internet, and many larger private Internet Protocol (IP) networks, rely on the Domain Name System (DNS) to help direct traffic.
  • 3. Jainul 3 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux The DNS maintains a distributed database of network names and addresses. It provides methods for computers to remotely query the database. Some people call DNS the "phone book of the Internet."
  • 4. Jainul 4 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux Domain Name Service (DNS) is an Internet service that maps IP addresses and fully qualified domain names (FQDN) to one another In this way, DNS alleviates/relieves the need to remember IP addresses.
  • 5. Jainul 5 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux DNS Servers and Name Hierarchy • DNS uses client/server network architecture. • DNS servers are the computers designated to store DNS database records (names and addresses), while clients of the DNS include PCs, phones and other devices of end users.
  • 6. Jainul 6 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux DNS Servers and Name Hierarchy • DNS servers also interface with each other, acting as clients to each other when needed. • The DNS organizes its servers into a hierarchy.
  • 7. Jainul 7 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux
  • 8. Jainul 8 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux • For the Internet, so-called root name servers reside at the top of the DNS hierarchy • The Internet root name servers manage DNS server information for the Web's top-level domains (TLD) (like ".com" and ".uk"), specifically the names and IP addresses of the original (called authoritative) DNS servers responsible for answering queries about each TLD individually.
  • 9. Jainul 9 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux • Servers at the next lower level of the DNS hierarchy track second-level domain names and addresses (like "about.com"), and additional levels manage Web domains (like "compnetworking.about.com").
  • 10. Jainul 10 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux
  • 11. Jainul 11 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux The domain name is a component of a Uniform/universal Resource Locator (URL) used to access web sites… for example: URL: http://www.w3schools.net/index.html Top-level domain name: net Second-level domain name: w3schools.net Host name: www.w3schools.net
  • 12. Jainul 12 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux • Computers that run DNS are called name servers. • Ubuntu ships with BIND (Berkley Internet Naming Daemon), the most common program used for maintaining a name server on Linux.
  • 13. Jainul 13 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux Installation • At a terminal prompt, enter the following command to install dns: $ sudo apt-get install bind9
  • 14. Jainul 14 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux Implementation of BIND • BIND is an acronym for the Berkeley Internet Name Domain project, which is a group that maintains the DNS-related software suite that runs under Linux. • The most well known program in BIND is named, the daemon that responds to DNS queries from remote machines.
  • 15. Jainul 15 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux Implementation of BIND • A DNS server does not know all the IP addresses in the world, but networks with other DNS servers which it can query to find an unknown address. • Most UNIX systems can run named, which is part of the bind (Berkeley Internet Name Domain) package distributed by the Internet Software Consortium.
  • 16. Jainul 16 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux Implementation of BIND • It can run as a stand-alone caching nameserver, which is often done on Linux systems in order to speed up network access. • Your main client configuration file is /etc/resolv.conf , which determines the order in which Domain Name Servers are contacted:
  • 17. Jainul 17 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux Implementation of BIND • search somewhere.org • nameserver 192.168.42.1 • nameserver 193.74.208.137 bind9 name server installation for DNS -On Ubuntu Linux server apt-get install bind9 dnsutils -Fedora alternative: yum install bind dnsutils
  • 18. Jainul Domain Name Server [DNS] 18 • Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux In computer networking, reverse DNS lookup or reverse DNS resolution (rDNS) is the determination of a domain name that is associated with a given IP address using the Domain Name Service (DNS) of the Internet. • Computer networks use the Domain Name System to determine the IP address associated with a domain name. This process is also known as forward DNS resolution. Reverse DNS lookup is the inverse process, the resolution of an IP address to its designated domain name.
  • 19. Jainul 19 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux • A DNS server, or name server, is used to resolve an IP address to a hostname or vice versa.
  • 20. Jainul 20 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux You can set up four different types of DNS servers: 1. A master DNS server for your domain(s), Which stores authoritative records for your domain. 2. A slave DNS server, Which relies on a master DNS server for data. 3. A caching-only DNS server, Which stores recent requests like a proxy server. It otherwise refers to other DNS servers. 4. A forwarding-only DNS server, Which refers all requests to other DNS servers.
  • 21. Jainul 21 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux The entire hostname with its domain such as server.example.com is called a fully qualified domain name (FQDN). The right-most part of the FQDN such as .com or .net is called the top level domain, with the remaining parts of the FQDN, which are separated by periods, being sub-domains.
  • 22. Jainul 22 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux • These sub-domains are used to divide FQDN(Fully Qualified Domain Name)s into zones, with the DNS information for each zone being maintained by at least one authoritative name server. • The authoritative server that contains the master zone file, which can be modified to update DNS information about the zone, is called the primary master server, or just master server.
  • 23. Jainul 23 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux • The additional name servers for the zone are called secondary servers or slave servers. • Secondary servers retrieve information about the zone through a zone transfer from the master server or from another secondary server. • DNS information about a zone is never modified directly on the secondary server.
  • 24. Jainul 24 Domain Name Server [DNS] Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-Linux-LinuxLinux-Linux-Linux-Linux • NEXT …. • Configuring DNS…