- DNS stands for Domain Name System.
- DNS is like a contact book, stored with Name of the Site and Its IP.
- DNS server checks the name and IP of the server in its table.
- Sends the IP to the host PC.
Why DNS came to existence:
- Every PC understand the address in the form of numbers.
- But for a person it is hard to remember a 32 number address, so created a name to each service.
- In order to make communication between the IP and Domain Name DNS is implemented.
Look Up in DNS:
- Forward Lookup : Process from Domain to the Server and Server to Domain.
- Reverse Lookup : Process from Server to Domain and Domain to Server.
DNS Working with levels:
ISP DNS:
- At first when you type any website in your PC.
- PC or Router checks whether details are available with it and sends the IP address of website.
- IP not available sends to the ISP DNS server.
- ISP DNS server checks whether, the details available with it.
- If not asks the Root Server.
Root Server:
- Root Server is DNS server contains the details of the TLD servers.
- Root Server checks the address and sends the matching TLD server IP Address.
ISP DNS takes the information and requests the TLD Server.
TLD Server:
- TLD servers servers which have information of the Domain Servers.
- These are .com,.net,.org,etc file extension servers.
- Each file extension has separate server.
- TLD servers receives the packet and name of the site.
- Sends the name DNS Server IP to ISP.
ISP DNS takes the information and requests the Name Server.
Name Server:
- Name Server is the server where the details of the site are present.
- Each Domain Name as separate DNS Server.
- Receives the packet and sends information of site IP to the ISP DNS.
ISP DNS sends the IP to the User.
Primary vs Secondary DNS:
Primary DNS:
- Primary DNS is the basic server used in the system.
- It is the master of the DNS servers.
- It looks after the in flow and out flow DNS server requests.
- Manipulates are writes the details of DNS Servers in the Primary and Secondary DNS.
Secondary DNS:
- Secondary DNS is the extension to the primary.
- Where it acts a backup to the Primary DNS.
- It is can only read the Database and Request the Primary to manipulate.
- It stores the details of the DNS.