01-23-2017 11:08 PM
Hi all , now i am work at customer suppot department , i am facing big issue now, please help me how to solve decrease in Cache Hit Ratio for INFOBLOX DNS 4010, thanks all !
01-24-2017 08:01 AM
The CHR can be affected by many factors. For example, if services are restarted, there will be nothing in the cache so all queries would have to be resolved recursively instead of through the cache. Entries in the cache must also be refreshed periodically (controlled by TTL's) so that can also affect these numbers. Additionally, you may see a spike in queries which have not been resolved previously and thus would also not be in the cache.
Other possibilities include reaching the maximum size that the cache can grow to or even be indicative of an attack as a common attack vector is to flood servers with random queries. If you have the Infoblox Reporting solution implemented in your Grid, you can generate reports to see the top clients which are sending queries, or you can leverage the system logs, Traffic Captures or even DNS Statistics to evaluate what queries are hitting the server and if anything seems suspect or not. You might find it helpful to check the Infoblox knowledge base. For example: