Summarizing the previous articles of the help system, it is possible to develop several rules, keeping to which would help a user to ensure optimal operation rate of the program:

1.Try to check as long lists as possible, lists with millions of addresses are optimal.

2.Also don't forget, please, that the more addresses from the same domain there are in a list, the quicker it will be checked. Check of million addresses from one domain takes 2..4 minutes

3.Never use DNS servers that didn't pass testing.

4.Avoid using DNS servers that failed to pass all 7 of 7 tests, as well as slow DNS servers.

5.Never use less than five DNS servers, with great number of threads use at least one servers for every ten threads. Failure to keep to these rules might result in breakdown of computer networks.

6.Greater thread number not always ensures higher operating rate. Some operation systems are unable of managing great number of threads effectively; the channel width required for great number of threads might exceed actually available width, so further increase of thread number would result in lower operating rate.

7.Remember that DNS server lists needs to be checked and updated on a regular basis.

The following symptoms might show that High Speed Verifier doesn't work optimally:

1.The number of DNS errors occurred while checking a list is greater or equal to a half number of domains processed.

2.CPU and Internet channel usage rate is low.

3.Checking speed is much smaller than you could expect with your Internet connection speed. Assuming that check of one domain (not one email address!) requires 300..400 bytes of network traffic, you can calculate maximum possible number of domains checked per second. For example, with 33.6 kbps connection it would be about 10..15 domains. Please note that with non-uniform address list, readings of the address checking speed indicator might be misleading.

Diagnostics should consist of the following steps:

1.Check the DNS server list once again. Probably, some of the servers have become slow or don't work any more.

2.Make sure that size of the DNS server list meets recommendations of this article. Remember that adding new fast servers to the list would never have negative effect on HSV operating rate.

3.Open the Internet-channel and CPU usage monitor (see your operation system manual). Slowly change the number of threads until you achieve the best relation between the checking speed displayed by HSV and load of the Internet channel and CPU. Besides the checking speed indicator, also note how quickly the number of checked domains is changing, because readings of the speed indicator might be misleading with non-uniform lists.

4.Note changes in readings of the DNS error counter, and adjust the number of threads if the readings go beyond the optimal range.