Using name resolution in syslog-ng

The AxoSyslog application can resolve the hostnames of the clients and include them in the log messages. However, the performance of AxoSyslog is severely degraded if the domain name server is unaccessible or slow. Therefore, it is not recommended to resolve hostnames in syslog-ng. If you must use name resolution from syslog-ng, consider the following:

  • Use DNS caching. Verify that the DNS cache is large enough to store all important hostnames. (By default, the AxoSyslog DNS cache stores 1007 entries.)

        options { dns-cache-size(2000); };
  • If the IP addresses of the clients change only rarely, set the expiry of the DNS cache large.

        options { dns-cache-expire(87600); };
  • If possible, resolve the hostnames locally. For details, see Resolving hostnames locally.