Increase in domain resolution failures after upgrade to SMG 10.9.2

Products

• Messaging Gateway

Issue/Introduction

Following the upgrade to Messaging Gateway (SMG) 10.9.2 you begin to see an increase in domain name resolution failures in SMG. These failures may include failures to resolve the hostname of inbound connections to the Messaging Gateway as well as failures in resolving MX records and hostnames for email delivery. Often these failures will occur more frequently with some email domains than others.

malilog
hard DNS error 'Timeout while contacting DNS servers' during MX lookup of '[domain]'

Environment

Version: 10.9.2

Cause

Changes to the DNS resolution timeouts and retry schedule in both the default system resolver and the resolver used by the SMG MTA are making Messaging Gateway more sensitive to slow DNS resolution in some environments.

Resolution

To address this issue, apply Patch 10.9.2-300

Additional Information

• Installing and removing patches for Messaging Gateway