How to Configure DNS Load Balancing with Dual ISP IPs for Seamless Application Availability

How to Configure DNS Load Balancing with Dual ISP IPs for Seamless Application Availability

Customers may be using 2 ISP's for Network redundancy purpose. They may have a setup of Active - Active (Both ISP's Active) or Active - Passive (One ISP Active, when it fails then the other ISP becomes active)

DNS Load balancing can used to load balance the traffic between 2 ISP's IP address. This will distribute the traffic sequentially across both the ISP's.

To achieve DNS load balancing with round robin method, we will need to create two additional A records in the DNS Panel. Follow the below steps to create A records.

1 Add the First A Record
  1. Click on the option to Add Record or Create Record.
  2. Choose 'A' as the type of record.
  3. In the host or name field, enter the host name (e.g lb-myapps.mycompany.com).
  4. Enter the IP Address of the first server where your application is hosted.
  5. Optionally set the TTL (Time to Live), which is commonly set to 3600 seconds (1 hour), You will need to change this to as minimum as possible.(1 Min)
  6. Save the record.

2. Add the Second A Record
  1. Click on the option to Add Record or Create Record.
  2. Choose 'A' as the type of record.
  3. In the host or name field, enter the host name (e.g lb-myapps.mycompany.com).
  4. Enter the IP Address of the second server where your application is hosted.
  5. Optionally set the TTL (Time to Live), which is commonly set to 3600 seconds (1 hour), You will need to change this to as minimum as possible.(1 Min)
  6. Save the record.
3. Verify the Records

After adding both the records, its important to verify that they are set up correctly. Use DNS lookup tools such as nslookup or dig for verification.

nslookup lb-myapps.mycompany.com
dig lb-myapps.mycompany.com

These commands should return both IP addresses that you configured for the A records.

4. Pointing SiteWALL WAF to send the traffic to new configured hostname pointing to these A records.

  1. Login to https://admin.sitewall.net 

  2. Go to Menu --> Configurations --> Application

  3. Click on Edit icon below Actions --> Edit Application

  4. Enter the hostname (lb-myapps.mycompany.com) in IP address tab

  5. Click on NEXT. You will receive a popup stating configuration saved.
  6. Click on CANCEL to save and exit.

After these DNS updates and adding the record in the SiteWALL portal, traffic will be efficiently routed based on your configurations to both the IP's