Update error-0xa8b-resolve-dns-fail.md

Author: Simonx Xu

support/windows-server/active-directory/error-0xa8b-resolve-dns-fail.md

@@ -7,7 +7,7 @@ audience: itpro
 ms.topic: troubleshooting
 ms.reviewer: kaushika, raviks, v-lianna
 ms.custom:
-- 'sap:active directory\on-premises active directory domain join'
+- sap:active directory\\on-premises active directory domain join
 - pcy:WinComm Directory Services
 ---
 # Error code 0xa8b: An attempt to resolve the DNS name of a DC in the domain being joined has failed