What is a DNS domain name server?

Every computer, network device participating in the Internet "talks" with each other by IP (Internet Protocol) address. To facilitate the use and easy to remember, we use the name (domain name) to identify the device. Domain Name System DNS (Domain Name System) is used to map domain names to IP addresses. Therefore, when they want to contact machines, they only need to use the easy-to-remember string (domain name) such as: www.microsoft.com , www.ibm.com ., instead of using the IP address as a long, difficult number to remember.

Domain name servers (DNS Servers) are servers that are installed, and provide DNS domain resolution services. DNS server is divided into 2 categories as follows:

Primary DNS Server (PDS)

Primary DNS Server (PDS) is the official information authentication source for domains that it is allowed to manage. Information about a domain managed by a PDS is stored here and can then be transferred to the Secondary DNS Servers (SDS).

PDS-managed domains are created, modified at PDS and then updated to SDS.

Secondary DNS Server (SDS)

DNS is recommended to use at least two DNS servers to store addresses for each zone. PDS manages the areas and SDS used for backup storage for the region, and for PDS as well. SDS does not have to be available but it is recommended to use it. SDS is allowed to manage domain names but domain name data is not generated from SDS but is taken from PDS.

SDS can provide no-load operation on the network. When the amount of query in the zone increases, PDS will switch the load to SDS (this process is also called load balancing), or when PDS is in trouble, the SDS works instead until the PDS becomes active. again .

SDS is often used in close proximity to workstations to serve queries easily. However, installing SDS on the same subnet or the same connection with PDS is not recommended. That will be a good solution to prevent PDS, because when connecting to PDS is broken, it will not affect SDS.

In addition, PDS always maintains a large amount of data and frequently changes or adds new addresses to regions. Therefore, the DNS server uses a mechanism to transfer PDS information to SDS and store it on disk. When it is necessary to restore data to regions, we can use the whole (full) solution or just take the change (incrememtal).