Cannot ping PostgreSQL in private subnet from a VM in public subnet

Question

I have a private subnet in VNet 1 with Network Security Group only allowing inbound traffic from a specific private IP CIDR. This subnet hosts Azure Database for PostgreSQL with a server name.

I also have a public subnet in a different VNet (VNet2) that hosts a standard VM.

I have done VNet peering to connect the two and they don't overlap the address spaces. I have also whitelisted the Private IP of the VM (in VNet2) in the NSG of Private subnet in VNet 1 but I cannot ping the PostgreSQL DB from my VM. It says:

ping: mydb-dev.postgres.database.azure.com: Name or service not known

Both VNets are in same subscription and same region

Answer 1

Things to be notice.

• You can't ping directly with server name ping mydb-dev.postgres.database.azure.com . Because this domain/server name is not registered in any public or private DNS Zone . If you want to ping with Server name your domain should be registered in DNS record.

• Another more imortant things is you need to open port default PostgreSQL port is 5432 at both the Vnet for inbound and outbound level.

• you are able to ping when your deploying both the resource in one VNEt.So By default, there is no security boundary between subnets for a VNet, so VMs in each of these subnets can talk to one another.