DNS servers are often a single point of failure that could cause your company's Web sites to vanish. Redundancy and solid diagnostics are critical. At Comdex, Men and Mice introduced their new line of DNS diagnostic and repair products. The Microsoft site outage in January of this year brought attention to the crucial, yet often neglected issue of DNS server configuration. A single point of failure -- in this case, the sole router for Microsoft's DNS servers -- caused many of the company's principle sites to vanish temporarily. To prevent such a crisis, redundancy is essential, and not just in terms of Web servers. If you extend your company's DNS servers across multiple network segments, a failure such as Microsoft's outage is much less likely. Add Active Directory to the equation, and the situation becomes even more challenging. To that end, Icelandic company Men and Mice is introducing a new version of its DNS Expert product -- a diagnostic tool that tests DNS servers for problems and suggests possible solutions -- specifically for Active Directory environments. Targeted at Active Directory administrators and project managers, DNS Expert AD diagnoses and solves DNS-related issues in Active Directory environments, featuring 20 new tests designed specifically for Active Directory. In total, DNS Expert AD runs 70 tests on DNS and Active Directory. Along with internal DNS/AD troubleshooting, DNS Expert AD can also detect problems with external DNS to ensure the reliability of your company's Web sites. DNS Expert AD, which is expected to ship before the end of the year, grabs data directly from the Active Directory and DNS data via zone transfers, then compares zone data to Active Directory data. It also scans the complete Active Directory environment periodically. Not everyone wants to get intimate with DNS. But once you finally get DNS servers up and running, the job doesn't stop there; you still have to keep tabs on them, or risk suffering crises. Due to the complexity of maintaining DNS servers, some IT managers may wish to outsource DNS management rather than allocate resources to training or to hiring new staff. Men and Mice's new Domain Health Care Service -- essentially a "DNS Expert online" for external DNS only -- provides 24/7 DNS health monitoring to keep your site safe from malicious attacks. Users can specify which of the 70-odd tests are performed, and define notification and reporting parameters. Currently, Men and Mice is offering the service to customers at the SOHO level, at less than $100 per month; a fully functional, 30-day trial of the service is available. The enterprise version of the service, scheduled to launch in Q1 2002, will start in the range of $500 per month. More enterprise IT news in ZDNet UK's Tech Update Channel For full Comdex coverage see ZDNet UK's Comdex '01 News Special. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet news forum. Let the editors know what you think in the Mailroom. And read other letters.