Hey @Valery_Mbele,
Welcome to the community 
i really don’t know what is the ip adress or dns resolver.
How to fetch that ? I tried with cluster0.refc9.gcp.mongodb.net , but it seems not valid.
cluster0.refc9.gcp.mongodb.net won’t directly resolve in an IP address(es) as it’s an SRV record. For some instructions on how to retrieve the IP addresses of the nodes within the cluster, please see the details within this post.
Hope this helps
Jason