2.7 Error Handling
Many error conditions can occur with Communications Server. Also, Communications Server is dependent on the successful operation of other systems. An exhaustive list of possible failures is not within the scope of this overview document; however, the following list provides categories where error conditions can occur.
Possible failures caused by dependent systems:
Unavailability of a local Global Catalog (GC) server for Active Directory requests.
DNS is not properly resolving protocol server fully qualified domain name (FQDN) or SRV records are not configured properly.
The certification authority (CA) that is used to issue certificates to Communications Server is not configured to be trusted by a protocol server or protocol client.
The hardware load balancer is not properly configured.
The SIP/PSTN gateway is not properly configured.
The RCC gateway is not properly configured.
Internal firewalls are blocking connectivity between protocol servers or between Communications Server and dependent systems such as GCs and CAs.
The reverse proxy is not properly configured.
A protocol server that is not running Communications Server is using incompatible protocols and extensions.
Possible failures caused by Communications Server:
An improperly configured or missing certificate.
Dependent components or redistributables are not installed.
Users are not configured for Unified Communications.
Administrative settings are not configured.
Incompatible protocols and extensions are being used by protocol clients.
For more information about these errors, see [MS-OCER].