Case Study - Defending against DDoS attacks, improving DNS management, and enhancing web redirects

What is a Backup DNS Zone?

What is a Backup (Secondary) zone?

The Slave/Backup DNS zone also known as Secondary is the read-only copy of the DNS records. This means that the DNS records cannot be added directly to the Slave/Backup DNS zone. The Slave/Backup DNS zone can receive the updated records only from the Master zone of the DNS server. The records in the Slave/Backup zone can be managed only at your master server. The Slave/Backup zones are available only for premium customers.

How does a Backup DNS zone work?

The DNS operates in a hierarchical manner, with multiple DNS servers responsible for resolving domain names. When a user attempts to access a website, their device queries the DNS server for the corresponding IP address. In a standard DNS setup, the user's DNS resolver typically contacts the primary DNS server associated with the domain.

In the event of a failure or unavailability of the primary DNS server, the Backup DNS Zone comes into play. When properly configured, the Backup DNS Zone allows the secondary DNS server to step in and serve DNS records for the domain. This ensures that even if the primary DNS server is unreachable, users can still access the website or service by resolving domain names through the backup server.

How to add Backup (Slave) zone in ClouDNS?

Login in your account, click on the DNS zones [Add new] link, click on the Secondary (Backup) zone box, enter the domain name (without www or http://), enter the Master Server IP and click on "Add slave".

How to add Backup zone in ClouDNS - Step by Step:

Dynamic DNS and Backup DNS

Dynamic DNS is a method to automatically update DNS records in real-time when the IP address of a host changes. While DDNS is typically associated with home networks and dynamic IP addresses, it can also play a role in backup DNS zones. Why? Because when the IP address of the primary DNS server changes, DDNS can be used to update the secondary DNS servers' records automatically. This dynamic synchronization ensures that the backup DNS zone always has the latest IP address information, minimizing downtime due to IP address changes.

FAQs 

Question: Why do I need a Backup DNS Zone if my primary DNS server is reliable?

Answer: While your primary DNS server may be reliable, unforeseen events like hardware failures, DDoS attacks, or network outages can lead to its temporary unavailability. A Backup DNS Zone acts as an insurance policy, ensuring continuous DNS resolution even if the primary server experiences downtime.

Question: What is the best TTL value for DNS records in a Backup DNS Zone?

Answer: The TTL (Time-to-Live) value determines the duration for which DNS information is cached by resolvers. A balance must be struck between lower TTL values for quicker propagation during failover and higher TTL values to reduce query traffic. Common TTL values range from a few minutes to several hours.

Question: Can I manually update the Backup DNS Zone when changes occur on the primary DNS server?

Answer: While manual updates are possible, they are not recommended due to the risk of discrepancies between the primary and backup zones. Automating DNS record synchronization is a more reliable approach to ensure consistency.

Question: What happens if the Backup DNS Zone itself becomes unavailable?

Answer: To address this, consider setting up multiple secondary DNS servers, strategically located in different geographic regions. This approach ensures further redundancy and minimizes the risk of the Backup DNS Zone becoming unavailable. 


Last modified: 2023-08-03
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