Tutorial on how to configure DNS Failover for Web Servers with DnsMadeEasy
- Only available for A records
- Three monitoring locations with 2-4-minute monitoring intervals
- Downed IP addresses are verified by multiple locations before failover events occur
- It will not monitor 2nd or 3rd IP addresses until the first is verified as down
Refer to constellix for more advance features, like
- Support for A, AAAA, ANAME, and CNAME records.
- Global Load Balancing, Advance Health Checking, Round Robin, and etc
What is DNS Failover?
DNS Failover keeps sites and web services online in the event of system or network issues. This is done by moving DNS traffic from one IP address to another IP address that you have running at another location.
Failover is most used to move traffic off an unhealthy web server and redirect it to a preconfigured backup web server.
We had prepared 2 x Reverse Proxy for Nginx with Kemp VLM in different Data Center for this lab as below
A Record for Primary Web Server
Create a contact list for Notification Email
Create a A Record for uat.aventislab.info to 22.214.171.124 with shorter Time to Live (TTL) between 180 to 300
Turn on SM/FO with the settings below
- Monitoring Notification – Enable for notification Email
- System Description – Enter a friendly Name
- DNS Failover = Enabled
- Turn Off Auto-failover after first failure – DNS Failover will not revert traffic back to the primary IP address automatically.
- Location 1 – Primary IP of uat.aventislab.info
- Location 2 – Secondary IP of uat.aventislab.info
- Protocol – Select TCP
- Port to monitor – Select 443
DNS Failover is NOT working if we set it to HTTPS with FQDN as below
DNS Failover for Web Servers
Shutdown Primary Web Server
- Verify the Primary Web Server is reachable
- Shutdown the Primary Web Server
- Email Notification will be delivered to alert you that the primary IP is down
- Login to DNSMadeEasy to verify the IP Address of uat.aventislab.info had switched to Secondary IP Address
- Verify https://uat.aventislab.info is accessible via secondary IP Address
Power on Primary Web Server
- Receive an Email Notification the Primary IP is online again
- A Record changed back to Primary IP Address
- Verify https://uat.aventislab.info is accessible via Primary IP Address now