Failed to process replication task Error: resolve: No such host is known

[Jonathan]

Hi guys,

I'm trying to replicate to a standalone Hyper-V host, but the job fails with the error: Failed to process replication task Error: resolve: No such host is known.

My setup is like this: the Hyper-V cluster and Veeam backup server on the service provider's network as a rental. The Veeam backup server has a second network interface in one of my subnets. On this same subnet I have a standalone 2016 Hyper-V host I want to use as a replication target and a backup repository. I added this server in the Veeam console, both as a repository and as a Hyper-V host. I can browse the contents of the SMB shares using the same account. I've added the server by FQDN, which is in the Veeam backup servers local hosts file.

I've already established the Veeam Backup server can resolve the FQDN just fine. There's also no routing or firewalling involved. I've rebooted the server. I've added the Hyper-V host by it's IP address rather than the FQDN. None of which got me any further.

Any ideas?

[nielsengelen]

You can check the relevant job log in %ProgramData%\Veeam\Backup<Job name> and you may find the resolution in there however if this doesn't provide additional help, feel free to contact support for insight and assistance.

[Jonathan]

Unfortunately, the job log does not provide any additional clues.
I can't contact support directly as the Veeam licenses are held by my service provider and getting them involved usually doesn't get me anywhere.

[nielsengelen]

Are you running firewalls on those servers (or maybe via the provider)? It might be this is actually causing the issue and the error is misleading to think it's a DNS error.

[Jonathan]

The only two firewalls involved are the Windows firewalls on the Veeam backup server and the Hyper-V host. I've turned both off to see if it would make a difference, but it didn't.

[Mike Resseler]

Jonathan,

Without thorough look into the logs by our support department, this is going to be guessing... Normally this error means that Veeam backup server cannot get to the host. Which could be the server where you replicate to or the cluster. Now you say there is no firewall, but is Windows firewall on? On any of these devices?
How are you pinging the cluster? By FQDN of the cluster? Can you resolve that without any issues?

[Jonathan]

The backup server can reach both the Hyper-v cluster (source) and the standalone Hyper-V host (target) by FQDN. Windows firewall has been turned off for testing, but it did not make a difference.

I'm struggling to understand why I can add a standalone host to the Veeam backup infrastructure and browse its contents, but the actual replication job can't find it. It cannot have anything to do with Hyper-V itself, because adding this server as a simple SMB share and using it as a backup target results in the same error.

There is something interesting in the networktest.log though:

connecting to '[target current ip address]:2500;[target old ip address]:2500;[even older target ip address]:2500;[target fqdn]:2500

Now, the first and the last entry should work fine. Both I don't get where the middle two ip addresses are coming from. Neither of those are in the hosts file or in the Veeam infrastructure configuration. I've already rebooted the Veeam server, so it can't be cached.

[Dima P.]

Jonathan,

Please open a support case as at this point debug log analysis is required to understand the root cause and provide the solution. Please do not forget to share the case ID. Thanks!

[giessle]

Cause we have different dns servers ....

Where should I take care of the dns resolution / dns suffix? VBR-Server? Repository-Server (Storage)? Or Hyper-V-Host?
"Processing VMxy Error: resolve: No such host is known" is the only message I got.

VBR 9.5 Update 4
OS: Windows Server 2016
Hyper-V 2012 R2

[ejenner]

Has this ever worked or was it working fine and became an issue?

[PTide]

Hi @giessle,

As per forum rules, kindly open a support case and post the case ID. Without the actual logs we can only guess.

Meanwhile, please check this BP guide for initial directions.

Thanks!

[foggy]

Agree on opening a case, but I'd also check if Hyper-V host can be resolved from Veeam B&R by its NetBIOS name.

[Jonathan]

I'm glad to report we have since moved back to a self-maintained vSphere cluster and a new in-house Veeam B&R server. A rented multi-tenant Hyper-V/SCVMM environment was hell on earth. All is well now...