Corp names stopped resolving
Spoke 2 can't find any corp.contoso.com servers.
- Get vm-spoke2 resolving app.corp.contoso.com and reaching it on 443
- Keep Spoke 1 resolving itbroken
Background
"The new Spoke 2 can't find any corp.contoso.com servers. Spoke 1 is fine." vm-spoke2 needs app.corp.contoso.com, an on-premises server, on 443. Spoke 1 gets corp.contoso.com names from dns-onprem through the hub's DNS Private Resolver, dnspr-hub, and its ruleset, rs-onprem. Spoke 2 was built last week from a network template.
- 1See it fail
Prove the problem yourself before you change anything. Reports are often wrong.
VM commands forVMsssh vm-spoke2What's this?
Opens a shell on vm-spoke2, so the next commands run on that VM. In this lab it's a shortcut. In real Azure you'd connect through something like Azure Bastion, or SSH to an address you can reach.
nslookup app.corp.contoso.comWhat's this?
Asks the VM's DNS server what IP address a name points to. Run it on the VM that has the problem, because each VM can get a different answer.
nc -zv app.corp.contoso.com 443What's this?
netcat, a standard Linux tool. Tries to open a TCP connection and reports whether it worked.
-zonly check whether the port answers. Send no data-vprint the result in wordsapp.corp.contoso.comwhere to connect443the port to try
Ticks off when the test runs on vm-spoke2.
- 2Find where it stops
- 3Name the cause
- 4Fix it and test again
?
- Resource group, the outer dashed frame
- Virtual network, with its address space top right
- Subnet, with range and usable IPs (5 reserved)
- Network security group. A small shield on a VM's NIC means the NIC has one too
- Route table on the subnet
- VM Appliance Private endpoint
- Peering Connected Initiated or access off
- Goal working Goal broken, X marks where it stops
- Private DNS zone, dotted lines go to linked VNets
- Orange pulse: what your last command changed. Drag to pan, Ctrl and scroll to zoom.
vm-spoke2 → app.corp.contoso.com:443should work: not working