DNS LookupLog files contain information about user hosts. It may be either a domain name or an IP address. For example 65.94.232.43 is an IP address of the user. We can resolve this IP address (do DNS lookup or, more accurate, reverse DNS lookup) and determine that this address corresponds to mtl-hse-ppp202789.qc.sympatico.ca. WebLog Expert uses domain names to determine top-level domains. In some cases IP addresses are already resolved in the log files. But usually they are not. WebLog Expert has a capability of resolving IP addresses. If this option is set to ON in the profile the program will do DNS lookups before analyzing logs. You must be connected to Internet during DNS lookup. The program uses multiple threads to perform DNS lookups. The program also caches the lookups. So if the program needs to resolve the IP name that is always in cache it won't need to repeat the DNS lookup. You can use the DNS Lookup category of the Options dialog to specify various lookup options:
DNS lookup information expires after N days. After the specified number of days passes since the lookup was performed, the program will try to resolve the IP address again.
Number of threads used during lookup. The default number of threads is 50 but if you have the fast Internet connection increasing this number may accelerate the lookup process.
Ask for confirmation before analyzing profiles with DNS lookup ON. This option may be useful because you must be connected to Internet while resolving IP addresses so the program will remind you of that.
Clear DNS Cache. Use this button to clear the program's DNS cache. | 
