vCenter deployed with a short hostname as PNID fails to perform file-based backup

Products

• VMware vCenter Server

Issue/Introduction

When performing a file-based backup of vCenter through the VAMI (port 5480), the process fails at 9x% with the following error message,

Backup PNID '######' is not resolved on the network. Configure the network DNS service accordingly.

(PNID, or Primary Network Identifier, is the system hostname used by vCenter Server during installation.)

In the log file /var/log/vmware/applmgmt/backup.log on the vCenter, the same error is observed,

YYYY-MM-DDTHH:mm:ss.### [########-######-########] [MainProcess:PID-#####] [Net::GetPNIDAddrInfo:Net.py:###] ERROR: Backup PNID '######' is not resolved on the network.
YYYY-MM-DDTHH:mm:ss.### [########-######-########] [MainProcess:PID-#####] [BackupManager::main:BackupManager.py:###] ERROR: BackupManager encountered an exception: Backup PNID '######' is not resolved on the network. Configure the network DNS service accordingly.

The vCenter is deployed with a short hostname ###### as its PNID, meaning that the hostname does not include a domain name. The content of the file /etc/resolv.conf is as follows,

nameserver <DNS server>
search ###.###.###

Here, ###.###.### represents the actual domain name.

On this vCenter the command 'nslookup ######' successfully resolves to its IP address because the search line in /etc/resolv.conf causes the system to treat the short name ###### as ######.###.###.### during name resolution.

 

Environment

vSphere vCenter 7.x

vSphere vCenter 8.x

Cause

vCenter does not use nslookup to resolve the PNID to an IP address. Instead, it uses the dig command for name resolution,

/usr/bin/dig +noedns +short +noadflag <PNID> a <DNS server>

Unlike nslookup, the dig command does not take the search line in /etc/resolv.conf into account. It directly queries the DNS server using the PNID as-is. As a result, since the PNID is a short hostname and not a fully qualified domain name (FQDN), the DNS server returns no result to the vCenter.

 

Resolution

Change the PNID from short hostname to FQDN, see Reconfigure the Primary Network Identifier