VMware Backup Proxy Disconnected Due to DNS Name Resolution Failure | Druva

Problem description

The VMware Backup Proxy is either invisible or displays a status of Disconnected on the Druva Phoenix Management Console. Additionally, backup, restore, or discovery tasks fail with socket-level DNS name resolution errors such as [Errno -2] Name or service not known or [Errno -3] Temporary failure in name resolution.

This scenario frequently occurs after static IP address assignments, network topology changes, or when the DNS server configured on the proxy becomes unreachable.

Cause

This issue is caused by the VMware Backup Proxy failing to resolve the FQDN/hostnames for the Druva Cloud endpoints or the vCenter Server. Common drivers include:

Incorrect or unreachable DNS server IP addresses assigned in the vApp network settings.
Missing or misconfigured nameserver entries in the proxy’s /etc/resolv.conf file.
Missing forward and reverse DNS lookup records for the vCenter Server.
Firewall or proxy rules blocking outbound DNS queries or outbound traffic on port 443 to *.druva.com.
The local Druva Phoenix service (/etc/init.d/Phoenix) on the proxy is stopped or unresponsive.

Traceback

Running a telnet connection test from the VMware Backup Proxy CLI fails with a hostname lookup error:

Bash

telnet phoenix.druva.com 443 telnet: phoenix.druva.com: Name or service not known | phoenix.druva.com: Host name lookup failure

Log entries recorded in /var/log/Phoenix/main_service.log:

Plaintext

[2020-04-22 17:39:12,826] [ERROR] Error <class 'socket.gaierror'>:[Errno -3] Temporary failure in name resolution. Traceback gaierror : [Errno -3] Temporary failure in name resolution.

Or during vCenter / Datastore operation checks:

Plaintext

'datastore': '<datastore_Name>', 'network_name': 'VM Network'} [2020-05-07 17:13:49,392] [ERROR] Error <class 'socket.gaierror'>: [Errno -2] Name or service not known. Traceback - Traceback (most recent call last):

Resolution

Step 1: Verify Basic Network & DNS Reachability

Open the Backup Proxy CLI (via SSH or vSphere Console).
Ping your configured DNS server IP address to confirm network reachability:
Bash
```
ping <DNS_Server_IP>
```
Ensure outbound traffic to *.druva.com on TCP port 443 is permitted through your network firewall.

Step 2: Check vApp Network Settings

Power off the VMware Backup Proxy VM in vCenter.
In the vSphere Client, navigate to the Backup Proxy VM > Configure > Settings > vApp Options > Networking Properties.
Verify that the DNS server IP address, Gateway, and Subnet Mask are accurate.
Save changes and power on the Backup Proxy VM.

Step 3: Verify and Update /etc/resolv.conf

Log in to the Backup Proxy terminal as root/sudo user.
Open /etc/resolv.conf using a text editor:
Bash
```
sudo vi /etc/resolv.conf
```
Ensure the file contains a valid, reachable DNS server entry:
Plaintext
```
nameserver <DNS_Server_IP>
```
Save and exit the file.

Step 4: Verify vCenter Forward/Reverse Lookup & Local Host File Mapping

Test forward and reverse DNS lookup for the vCenter Server from the Backup Proxy:
Bash
```
nslookup <vCenter_FQDN> nslookup <vCenter_IP_Address>
```
If DNS lookup fails, add an explicit static entry in the /etc/hosts file:
Bash
```
sudo vi /etc/hosts
```

Add the vCenter Server details:

Plaintext

<vCenter_IP_Address>   <vCenter_FQDN>   <vCenter_Hostname>

Step 5: Verify Druva Phoenix Service Status

Check if the Phoenix service is running on the backup proxy:
Bash
```
/etc/init.d/Phoenix status
```
If the service is stopped, start it manually:
Bash
```
/etc/init.d/Phoenix start
```

Step 6: Advanced Network Inspection (If issue persists)

Use network packet capture tools (e.g., tcpdump or Network Monitor) to inspect TCP/UDP packets on DNS port 53 and HTTPS port 443 to ensure responses are not being dropped by security software.
Reboot the VMware Backup Proxy VM as a final step to reset cached network configurations.

Verification

To confirm that the issue has been resolved:

Run a domain reachability test from the Backup Proxy CLI:
Bash
```
telnet phoenix.druva.com 443
```
Expected result: Connection establishes successfully.
Log in to the Druva Phoenix Console and navigate to Infrastructure > VMware. Verify that the status of the Backup Proxy has updated to Connected.
Run a manual discovery or test backup job from the console.