v8 new installation - can not add Windows-based Backup Proxy Servers

[lucaliga]

Hello,

My case is Veeam Support - Case # 07867954 - Proxy installation error
My VBM365 server has FQDN server05.tradate.ad
I want to add a new Windows-based Backup Proxy Servers on Windows machine FQDN SERVERPL24.zarow
Between domains zarow and tradate.ad there is a domain trusts and Networking works fine: Ping and nslookup are OK (using FQDN) between each other.
I selected the Use domain network check box when adding new proxy.
Installation fails at stage:
Configure proxy. Error: An attempt to connect to SERVERPL24.zarow has timed out.
the log from SERVERPL24.zarow in folder C:\ProgramData\Veeam\Backup365\Logs shows:
[Info] Using PostgreSQL database (connection string: Host=server05;Port=5432;Database=VeeamBackup365;Username=proxy_dbuser_veeambackup365;Maximum Pool Size=20;Connection Idle Lifetime=10;Command Timeout=30;Timeout=60;Password=***)...
[Error] Error: [EFCoreLogging]: An error occurred using the connection to database 'VeeamBackup365' on server 'tcp://server05:5432'.
[Info] Retry transient error after 00:00:00: SocketException: No such host is known.

The "Error: No such host is known." when trying "connection to database 'VeeamBackup365' on server 'tcp://server05:5432'." is quite clear to me.
The SERVERPL24.zarow try to connected "server05" which is single-labelled domains, thus DNS resolution fails then "No such host is known"

Now in the topic post556675.html#p556675 both flavio.santos and Polina wrote: proxies and the controller talk using server names. True but there is one problem: Veeam setup/installation of new Veeam Backup for Microsoft 365 server use the computername, aka netbios name, of the machine for both the PostgreSQL instance and the default backup proxy server, automatically and by default, assigned to the machine where Veeam Backup for Microsoft 365 is installed. In my case PostgreSQL database is "Host=server05" and default backup proxy server has name "server05".
This is not a problem when all your systems resides on the same domain because TCP/IP V4 in Windows (look at ipconfig /all) there is a parameter "DNS Suffix Search List" by default filled with the domain name. The DNS resolution try to resolve the name as it is, fails then try adding the "DNS Suffix Search List" and find it. On any computer joined to domain tradate.ad the command nslookup server05 returns the resolution server05.tradate.ad with its IP address.
But if you, like me, work with a network made by many different domains you have to manually configure each VBM365 component to guarantee the name resolution of the VBM365 server "server05" to "server05.tradate.ad" using or hosts file (bad way), used in TCP/IP name resolution before checking the Domain Name System (DNS) or (better way) add to each DNS server a CNAME . In my case in DNS server hosting AD zarow I have to add record server05.zarow CNAME point to server05.tradate.ad
Thus now SERVERPL24.zarow resolve server05 as server05.tradate.ad and adding backup proxy SERVERPL24.zarow returns: Backup proxy successfully installed.

Someone in Veeam could explain to me why you use the (weird) computername/netbios name instead of FQDN when creating objects during VBM365 server installation ?

Thanks

BR
Luca

[lucaliga]

I got this answer from Technical Support:
As investigated further, VB365 uses the machine’s NetBIOS name during installation and object creation, not the FQDN. All internal communications between VB365 components (including proxies) use this name, as this is a behavior by design.

But this is in contrast to https://helpcenter.veeam.com/docs/vbo36 ... tml?ver=80 where initial note state:
Veeam Backup for Microsoft 365 requires the Veeam Backup for Microsoft 365 server and a backup proxy server to be reachable to each other by their DNS name.

The only available solution is to add a CNAME to any AD DNS zone hosting a Proxy server