Domain Name System (DNS)

DNS (Domain Name System)Defination: The Internet's system for converting alphabetic names into numeric IP addressesDNS ModeName Resolve scenarioRoot Servers: this Main Server start with dot (.) and there are only 13 server around all over the worldTLD (Top Level Domain): is the highest level of domain names in the root zone of the DNS of the Internet, sample of these servers com,eg,gov,edu,org,netAuthoritative Server: it's DNS server holds a copy of the regional phone book that matches IP addresses with domain names.and responsible for providing answer about name in Zones. these zones add by server admin, like hosting web sites which has own Authoritative serverRecursive DNS server: The recursive resolver acts as a middleman between a client and a DNS nameserver. After receiving a DNS query from a web client, a recursive resolver will either respond with cached data. it reduce request needed from upper DNS server layer. like ISP DNSCache DNS server: work by performing all the DNS queries that your system makes and then savingDNS ProcessDNS ProcessZone Typeforward Zonereverse ZoneBIND (Berkeley Internet Name Domain) service on linux called named parameter related to Zone fileRR (resource record): each record write in this file called RRTTL (Time To live) value for the zone, that is, how long is a zone record valid, which mean when you increase TTL it will allow recursive server save this record long time and reduce requestA (address record): specifies an IP address to be assigned to a nameCNAME (Canonical Name record):it maps one name to another. Because of this, this type of record is sometimes referred to as an alias recordMX (Mail Exchange):record specifies where the mail sent to a particular namespace controlled by this zone should go. The email-server-name is a fully qualified domain name (FQDN) NS(Nameserver): record announces authoritative nameservers for a particular zonePTR (Pointer): it points to another part of the namespace. write last digit in IP then FQDN. use in reverse zoneSOA (Start of Authority):it record announces important authoritative information about a namespace to the nameserver. Located after the directives, it is the first resource record in a zone fileAuthoritative DNSPrimarySecondaryany change in primary file zone you must change file serial to allow DNS Update mechanism start transfer data from primary to standby. or you can use automatic method for update by use djbdns, DNS update mechanism use DNS Zone transfer use query type AXFRICANN (Internet Corporation for Assigned Names and Numbers)it is an internationally organized, non-profit corporation that has responsibility for Internet Protocol (IP) address space allocation, protocol identifier assignment, generic (gTLD) and country code (ccTLD) Top-Level Domain name system management, and root server system management functionsdig commandthis command use for DNS debug Tshoot on linuxexampleAhmed Bebars