Event ID - 6523

Event Id	6523
Source	Microsoft-Windows-DNS-Server-Service
Description	Zone %1 failed zone refresh check. Unable to connect to master DNS server at %2 to receive zone transfer. Check that the zone contains correct IP address for the master server or if network failure has occurred. For more information, see "To update the master server for a secondary zone" in the online Help. If available, you can specify more than one master server in the list for this zone.
Event Information	According to Microsoft : Cause : This event is logged when Zone failed zone refresh check. Resolution : Check the master DNS server If a zone transfer for a secondary zone on the local DNS server is failing, check that the zone is configured to use the correct master server. To perform this procedure, you must have membership in Administrators , or you must have been delegated the appropriate authority. To check the master server for a secondary zone: On the secondary DNS server, open DNS Manager. To open DNS Manager, click Start , click Administrative Tools , and then click DNS . In the console tree, expand the secondary DNS server, and then expand the folder that contains the zone. Right-click the zone, and then click Properties . On the General tab, confirm that the Master Servers list contains one or more servers that are authoritative for the zone. Click Edit , and then confirm that the IP addresses of the listed servers have been validated. If the configuration of the zone at the master DNS server appears to be correct, ensure that the master DNS server is functioning properly and that it can be accessed by the secondary DNS server. Verify : Verify that all DNS servers that are authoritative for a zone have the same serial number for the zone. To view the serial number for a zone: On the DNS server, open DNS Manager. To open DNS Manager, click Start , click Administrative Tools , and then click DNS . In the console tree, right-click DNS, and then click Connect to DNS Server . Click The following computer , type the DNS name or IP address of the secondary DNS server, and then click OK . In the console tree, expand the secondary DNS server, and then expand the folder containing the zone. Right-click the zone, and then click Properties . Click the Start of Authority tab, and note the value in Serial number . Note : If dynamic updates are enabled for the zone, or if an administrator changes the zone between the time that you check the master and secondary servers, the serial number on the master server can be slightly higher than the number on secondary servers.
Reference Links	Event ID 6523 from Microsoft-Windows-DNS-Server-Service

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