NNTP session Delays
The NNTP (i.e., news) session delay exceeds the critical value set in Expert Thresholds. The "session delay" metric combines network latency (i.e., the time spent waiting for data to traverse the network) and application processing time (i.e., the time spent waiting for the server or application to respond to a request). Application Processing Time for NNTP is tracked with a separate Expert Threshold.
Possible reasons for the event:
If application processing time is within reasonable limits, network latency must account for the bulk of the session delay. You should look for problems with the network. Do you have enough bandwidth between the application server and the clients that use it? Are the routers between the systems configured correctly?
If the Expert Threshold for application processing time is also being exceeded, the slowdown is probably the result of a server or application configuration issue. Perhaps the server hardware is overloaded with disk I/0 requests, or some other system component (NIC, processor) is too slow given the traffic it is expected to handle. There are many strategies for limiting the system resources that an NNTP server is allowed to consume. For example, you can delete newsgroups from your server or shorten the expiration policies for particular newsgroups.
If you do not want to limit your users' access in such ways, and still want to improve performance, you may want to set up virtual (also known as slave) NNTP servers that cache articles locally. The virtual servers all connect to the master server, but not too each other. You can then use round-robin DNS, a load balancing technique that assigns multiple IP addresses to the same DNS name.