SDDC Manager sos health-check shows Reverse DNS as YELLOW

Products

• VCF - MCOE - SDDC

Issue/Introduction

Alerts is the warning the SOS health check gave regarding the reverse lookup.

1. DNS Capitalization Issue : The reverse lookup from SDDC Manager shows hostnames in mixed case (e.g., "esxhost1.EXAMPLE.COM"), while all objects and environments follow a lowercase naming convention.
2. SOS Health Check Warning : SOS health checks are issuing warnings related to DNS consistency, indicating potential issues with workflows.
3. Forward/Reverse Lookup Success : Despite the warning, forward and reverse lookups resolve correctly.

Environment

VCF 5.x

Resolution

1. Inventory Review :

   • Confirm the naming convention of all ESXi hosts and other relevant nodes in the environment.
   • Verify that there are no inconsistencies between DNS entries and object names (e.g., hostname vs IP).

2. DNS Configuration Check :

   • Ensure that DNS zones and records follow a consistent case-sensitive format (lowercase preferred).
   • Review any DNS server configurations to ensure they handle lookups correctly without introducing mixed-case issues.

3. SDDC Manager Configuration :

   • Update SDDC Manager settings if possible to enforce lowercase naming conventions.
   • Check for any documented best practices or KB articles related to DNS and naming conventions in SDDC environments.

Review DNS Zones :

dig +short esxhost1.example.com (This will provide the Forward lookup IP in short format)
host xxx.xxx.xxx.xxx (This will provide the reverse DNS hostname for the IP)

1. Check SDDC Manager Logs :

   • Look for any logs or alerts related to DNS issues in the SDDC Manager.

2. Update Hostnames if Necessary :

   • If found, update any hosts that are inconsistent with lowercase naming conventions.

 

The mixed-case issue observed in reverse lookups from SDDC Manager could potentially cause workflow failures and other operational issues despite correct resolution of forward/reverse lookups. A thorough review and enforcement of consistent naming conventions across DNS and system configurations is recommended to mitigate these risks.