Health-check operation SDDC fails with DNS-check | Forward DNS lookup is NOT configured as expected

Products

• VMware SDDC Manager

Issue/Introduction

• DNS health check on SDDC fails with error.
• Running /opt/vmware/sddc-support/sos --dns-health also fails with error.
  DNS lookup Status : RED

"name": "sddc01.example.com: Forward DNS lookup check",
"status": "FAILED",
"message": "Forward DNS lookup is NOT configured as expected, resolved ip IPADDRESS is not equal to IPADDRESS",
"errors": "Forward DNS lookup is NOT configured as expected, resolved ip IPADDRESS is not equal to IPADDRESS"

• vcf-sos.log shows error logging similar to: /var/log/vmware/vcf/sddc-support/vcf-sos.log

INFO [vcf_sos] [progressreporter.py::update_task_status::299::_parallel_check_nsx_dns_configuredThread0] Overall status for DNS-CHECK : COMPLETED_WITH_FAILURE
INFO [vcf_sos] [progressreporter.py::update_task_status::338::_parallel_check_nsx_dns_configuredThread0] Current Status: Task-Name: DNS-CHECK, Entity-Name: edge02.example.com: Forward DNS lookup check, Task-Status: COMPLETED
INFO [vcf_sos] [progressreporter.py::determine_progress::108::_parallel_check_nsx_dns_configuredThread0] All Tasks : {'VCF-SUMMARY': 'NOT_COMPLETED', 'DNS-CHECK:nsx.example.com: Reverse DNS lookup check': 'COMPLETED', 'DNS-CHECK:vcsa01.example.com: Reverse DNS lookup check': 'COMPLETED', 'DNS-CHECK:sddc01.example.com: Reverse DNS lookup check': 'COMPLETED', 'DNS-CHECK:nsx.example.com: Forwar
d DNS lookup check': 'COMPLETED', 'DNS-CHECK:esxi03.example.com: Reverse DNS lookup check': 'COMPLETED', 'DNS-CHECK:esxi02.example.com: Reverse DNS lookup check': 'COMPLETED', 'DNS-CHECK:esxi04.example.com: Reverse DNS lookup check': 'COMPLETED', 'DNS-CHECK:esxi01.example.com: Reverse DNS lookup check': 'COMPLETED', 'DNS-CHECK:sddc01.example.com: Forward DNS lookup check': 'FAILED', 

Environment

SDDC manager

Cause

Issue is caused due to improperly formatted hosts file in the SDDC Manager.

Resolution

Check the sddc manager hosts file.

1. Login to the SDDC Manager and elevate to root using su - command.

2. Navigate to hosts file by using  below command

cat /etc/hosts

# Begin /etc/hosts (network card version)
# End /etc/hosts (network card version)
# VAMI_EDIT_BEGIN
# Generated by Studio VAMI service. Do not modify manually.

127.0.0.1   sddc01 localhost

# VAMI_EDIT_END

In this case as we can see loopback (127.0.01) is not associated with sddc-manager FQDN.

3. To fix the issue, edit the hosts file and make sure loopback entry is properly formatted like below

127.0.0.1 SDDCIPAddress SDDCFQDN SHORTNAME localhost

4. Re-run the health check and make sure DNS health check is GREEN using following command 

/opt/vmware/sddc-support/sos --health-check --domain-name ALL --skip-cert-check