Local DNS for 3 VPN connected sites

Question

I currently have 3 R Pis running Dnsmasq at 3 sites providing local name resolution. Each site is connected to the other two with LAN-to-LAN VPNs. Each site also has dial-in VPN access. I would like to add remote site name resolution but have been so far unsuccessful in configuring this.

Current config at each site:

domain-needed
bogus-priv
no-resolv
server="local isp dns"
cache-size=1000

Each DNS has a hosts file with all local and remote hosts.

Currently "PING 'remote host'" results in "Ping request could not find host 'remote host', Please..."

"PING 'remote IP'" works, ok.

However, "dig 'remote host' A +noall +answer" elicits its IP address.

My aim is to have the Windows Explorer network neighbourhood display all hosts.

Answer 1

DNS is unrelated to Windows Explorer Network display, you can verify that by configuring Windows to use a public DNS server with no knowledge of your internal hosts. You should still be able to find local hosts in Windows Explorer.

This is because Windows Explorer uses NETBIOS to discover hosts on the local network and WINS to resolve the NETBIOS hostnames.

Windows Explorer uses Network Broadcasts in your local networks to find hosts, and these Broadcasts have to reach all VPN subnets.

Sadly, I don't know how Windows handles this in detail, but I assume you need at least a static route to the VPN subnet(s) for Windows to recognize these networks are available locally, and/or a central WINS server that needs to be known on every client. Since you use site2site topology, clients are agnostic of the VPN subnet(s) and will just use the default gateway to reach those subnets.

You could also configure all hosts to be on the same subnet (10.0.0.0/8) with the appropriate broadcast address (10.255.255.255) and configure Routing and DHCP for subnets (10.10.0.0/16 for site1, 10.20.0.0/16 for site2, etc.) to form a single homogenous network.