Root Servers: this Main Server start with dot (.) and there are only 13 server around all over the world

TLD (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,net

Authoritative 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 server

Recursive 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 DNS

Cache DNS server: work by performing all the DNS queries that your system makes and then saving

DNS Process

DNS Process

forward Zone

reverse Zone

parameter related to Zone file

Primary

Secondary

any 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 AXFR

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 functions

this command use for DNS debug Tshoot on linux

example