Secondary DNS – Everything you need to know

Secondary DNS – What is it?

Secondary DNS, or also often called Slave or Backup DNS, is a great service that provides a network of DNS servers. They are secondary to your Primary DNS server. Their purpose is to duplicate the Primary DNS zone file automatically. That way, you could establish more points in the world where your DNS records are stored. They are available in a situation when your Primary DNS experiences downtime.

You can manage your DNS in the Primary DNS and remove, add or edit DNS records. On the other hand, you could choose a Secondary DNS service from the same DNS provider or a different one. If you really desire to have a strong backup of your Primary DNS, you could even use several Secondary providers.

The mechanism for copying the zone information from the Primary DNS to the Secondary DNS is called DNS zone transfer.

Primary DNS vs. Secondary DNS

Each DNS zone has only one Primary DNS server. There is kept all of the DNS zone information. If the DNS administrator has to make changes and adjustments, it has to configure them on the Primary DNS server. Therefore it is the main source of data for the other servers.

There are no restrictions on the number of servers for Secondary DNS. It could be just one or several, yet they are linked to a Primary DNS server. Backup DNS servers receive data from the primary DNS by the DNS zone transfer. It is a good idea to choose a different DNS provider for your Backup DNS because that way, the chance of failures affecting their websites’ performance (attacked servers, downtime, etc.) is highly reduced. In the meantime, you increase the redundancy. 

Every DNS server could act as a Primary DNS or Secondary DNS. In addition, a Primary DNS server for one DNS zone could operate as a Backup DNS for a completely different zone.


The benefits of implementing a Secondary DNS are a lot and significant ones.

  • Your Primary DNS won’t be overwhelmed. If the number of queries increases, you will be able to spread the weight and guarantee your website’s availability.
  • Relying on only a Primary DNS server holds risks in case of failure, error, or attack. Authoritative DNS records for the DNS zone are not going to be available. With Backup DNS, you won’t worry about this.
  • In a situation where your Primary DNS goes down, your website will continue to function for users through the Backup DNS. Solid uptime is crucial, and for online business means in terms of profits.
  • Fast response to users’ queries. If the users are far from the Primary DNS server, they will wait longer for an answer. Backup DNS servers strategically positioned in different places will provide high-speed replies.
  • Great user experience. Higher speed is beneficial for the user, such as less time for waiting for an answer and loading way faster. For sure, that affects the position of your website in the search engines’ results.
  • It is an excellent backup. If something happens to the Primary DNS, this is your ideal “plan B.” You can easily restore your DNS records with Backup DNS.
  • Secondary DNS is easy to enable, and all the modifications you do will be duplicated automatically.

Author: isabella

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