Discusses IP address resolution and implications for server resource usage.
When your web server generates a log file, it can either be configured to look up the client machine’s IP address as it creates the log file in a process known as reverse DNS, or it can leave the IP address unresolved. The more efficient approach is to look up the IP address during log file creation; however, because this process (known as Internet resolution) takes some of the server’s resources to perform this lookup, web site content delivery may be negatively affected. For this reason, many web servers are not configured to perform a lookup.
The reality is that when reviewing reports about your visitors, just receiving the IP address of your visitor does not give you much insight. An IP address can’t let you easily see that many of your visitors come from the competition, or that many of your visitors come from a company with whom you are trying to establish more business.
IP addresses also affect visitor counts, because multiple IP addresses can resolve to the same domain name.
Webtrends Analytics software gives you the option to look up IP addresses from DNS servers. After a lookup, Webtrends stores IP addresses in a cache so future analyses can use the information locally, rather than having to go through DNS servers to locate the information. You need to determine the value of having IP addresses translated into meaningful names versus the loss of disk space that the cache of resolved addresses occupies. Typically, the address cache has a size limit. When the cache reaches the limit the oldest entries are deleted to make room for more recent ones. Because DNS lookups use memory, you should also weigh the impact of looking up IP addresses on analysis performance.
Recommendations: Internet Resolution
- Determine how important it is to have the looked up values of IP addresses in your reports. The space required by these looked up values can be fairly minimal, but the performance slowdown can be noticeable. Most people tend to have the lookup performed if the Web server did not already do this.
- Note that a company may use many IP addresses that are assigned to them but only register a few of these addresses as domains. For example, a company may have many proxy servers with addresses that connect to the Internet, yet since the company doesn’t expect anyone to connect to the proxy, it hasn’t assigned a domain to the proxy. Consider using Webtrends GeoTrends, which will resolve IP addresses more accurately than DNS. That is, GeoTrends identifies the companies that registered the IP addresses. GeoTrends also provides pertinent geographic and demographic information for your web analysis.
To specify Internet resolution settings:
- In the left pane, click Administration > Web Analysis > Options > Analysis .
- Click Internet Resolution.