Load balnacing and DNS

I have two isp with subnets from ISP’s
I want to do inbound load balance.
Server A is nat ed with IP from ISP A and ISP B .
if ISP A is down traffic need to come from ISP B.
DNS service is hosted in ISP A.
Do I need to change the DNS from ISP to peplink .
If yes how can I do that
Please help