How to create a connection between two virtual networks?

I am trying to join a VM to a to a managed domain On Azure. I have checked on a Microsoft page but my issue it can be different. I can do a ping to 123test.com because it is a website and I am receiving a public IP address 69.x.x.x

I think that could be a cause of this issue. When I am trying to confirm by OK button I am receiving the error:

An Active Directory Domain Controller (AD DC) for the domain "123test.com" could not be contacted. Ensure that the domain name is typed correctly.

Note: This information is intended for a network administrator. If you are not your network's administrator, notify the administrator that you received this information, which has been recorded in the file C:\windows\debug\dcdiag.txt.

The following error occurred when DNS was queried for the service location (SRV) resource record used to locate an Active Directory Domain Controller (AD DC) for domain "123test.com":

The error was: "DNS name does not exist." (error code 0x0000232B RCODE_NAME_ERROR)

The query was for the SRV record for _ldap._tcp.dc._msdcs.123test.com

Common causes of this error include the following:

• The DNS SRV records required to locate an AD DC for the domain are not registered in DNS. These records are registered with a DNS server automatically when an AD DC is added to a domain. They are updated by the AD DC at set intervals. This computer is configured to use DNS servers with the following IP addresses:

168.63.129.16

• One or more of the following zones do not include delegation to its child zone:

123test.com

com . (the root zone)

you can workaround by using a hosts file inside your vm (to force this dns to resolve to IP of your domain controller), or you can configure your vnet to use your DC as a DNS server.

https://docs.microsoft.com/en-us/azure/virtual-network/virtual-networks-name-resolution-for-vms-and-role-instances#specify-dns-servers