The Domain Name System is how you connect to websites. It’s a system that matches human-readable domain names, like junaidtariq.com, with the unique ID of servers where websites are stored.
The DNS system is the internet’s phone directory. It maps domain names (junaidtariq.com) to their corresponding IP addresses, instead of mapping people’s names to their phone numbers. If a user enters wpbeginner.com on his/her device, the DNS system’s job is to map the domain to its physical location (URL) and then connect him/her to the site from there.
Types Of DNS Servers
A DNS Server completes the process of name resolution in DNS. They contain zone files that enable them to resolve names to IP addresses and vice versa.
DNS Servers might ask for resolution data from other DNS Servers, but that is it. Beyond that, a DNS server provides answers to questions solicited by other computers.
There are three common types of DNS servers: primary servers; secondary servers; and caching servers.
Primary Server
The primary server is in charge of the zone. All administrative tasks related to editing the zone, such as creating subdomains or changing statistics, must happen on the primary server. If you’re integrating Active Directory services or Microsoft DNS servers, there will be one primary server unless you specify otherwise.
Secondary Server
Secondary servers are backup DNS servers that receive all their zone files from the primary server. This ensures that there’s no interruption in service should the primary server go down and removes load time overhead incurred by an upstream authoritative source as is expected of them to do. They also serve to offer load-balancing, fault-tolerance, and traffic reduction for your server. In conclusion, any given secondary DNS can act as one for up to and beyond a single domain or domain zones.
In addition to the primary and secondary servers, additional server roles can be implemented when appropriate for an infrastructure. These servers are caching servers and forwarders.
Catching Server
Caching servers are used to store records of the recent queries that they have seen, providing a quick answer without the need to go search the domain zones. They save time as well as bandwidth when looked at as a whole. However, they would not update any domain records, which is not what happens with other secondary servers (that go through and make sure that domains are being changed appropriately).
Types Of DNS Service
DNS is a global system for translating numerical IP addresses to human-readable hostnames. When you try to access a website like “example.com”, your web browser sends a request for the website’s DNS server and provides the domain name. The server resolves this domain name into its numeric IP address for connection, which your browser can then access.
A DNS Resolver is a component that’s responsible for checking if the hostname is available in the cache. If not, it queries a series of DNS Name Servers until it receives the IP of the website or service you’re trying to reach, then returns it to the browser or application.
Authoritative DNS Service
An authoritative DNS service provides an update mechanism that developers use to manage their public names. It then answers queries, translating domain names into IP addresses so computers can communicate with each other. An authoritative DNS has the final authority over a domain to provide answers to recursive servers with the IP address information.
Recursive DNS Service
Generally, clients don’t contact authoritative DNS servers directly. They will instead get a DNS server that acts as an intermediary. A recursive or caching DNS can be thought of as a hotel concierge: they’re not the source, but they’re happy to pass your request along to someone who can provide the information you’re looking for.
