Scenario:

• You have at least two datacenters running the same application and both datacenters are simultaneously active (business continuity)
• Your application is mapped on a well-defined hostname (ie. www.myapplication.com)
• On the first datacenter www.myapplication.com is running on IP a.b.c.d. One the second datacenter www.myapplication.com is running on IP x.y.z.t
• You need to monitor your application health using IP addresses that are different from a.b.c.d and x.y.z.t

 

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Solution:

• Use GSLB.me in round robin balancing mode
• Define one geohost that will be pointed by www.myapplication.com via a DNS CNAME record
• Create two targets, one for each datacenter and define their aliases. Targets will be healthcheck-monitored using their IP addresses but GSLB.me will resolve the geohost name using the aliases.
• Assign the relevant checks to each target
• Configure the CNAME record on the primary DNS server that handles the domain myapplication.com

How to configure it:

1. Register on GSLB.me and log on
2. Select under which one of the available domains (gslb.us, gslb.info, …) you want to create your geohost. You can choose the domain you prefer, this is purely a “cosmetic” choice. Let’s choose mywebsite.gslb.eu
3. Create your geohost: a geohost is the FQDN (Fully Qualified Domain Name) that your authoritative DNS will use as a CNAME for your application hostname (ie. www.myapplication.com). Select “Round robin” as your balancing algorithm. This will enable active-active distribution of incoming traffic towards your datacenters
4. Define the first target: the target’s IP address is a.b.c.d and we are setting its alias IP address
5. Select checks to be performed on the first target
6. Define the second target: the target’s IP address is x.y.z.t and we are setting its alias IP address
7. Select checks to be performed on the second target
8. Configure your authoritative DNS to use a CNAME record to have www.myapplication.com point to mywebsite.gslb.eu