Rooting Out DNS Errors - continued

Fixing as well as finding
If DNS Expert Pro merely reported existing problems, it would certainly be useful, but you'd still be left to figure out the meaning of messages such as "the name server 'dns2.microsoft.com' is not listed in delegation data." Thankfully, Men and Mice provides both an onscreen explanation of the error, and then, via a link back to its website, additional info on how to solve it. Ultimately, you'll need to understand what terms such as "delegation" mean, however, so keep those O'Reilly books, or others like them, handy.

Testing my own domains turned up several errors—hardly surprising considering how often domain entries are made in the heat of battle to "get things working." But I was a bit shocked running DNS Expert Pro against major companies's domains (Microsoft, IBM, Yahoo, etc) and seeing just how many contain errors of one sort or another. For instance, DNS Expert revealed that Microsoft's main five mail servers could act as relays, and that four of its DNS servers were vulnerable to spoofing. Interestingly, for all the heat it gets about customer service, AOL was the only major domain I tested that didn't have any DNS setting errors. (Maybe someone down in Virginia has a copy of DNS Expert Pro on their shelf?)

By the way, you don't need to worry about what type of DNS server is running on the other end. DNS Expert can analyze DNS records on pretty much any DNS server in use, including all versions of BIND (v4.x and v8.x), and other domain name servers on UNIX, Linux, NT, Mac OS, and other operating systems.

The other three faces
The three other DNS Expert modules (DNS Query, Ping, and Trace Route) are primarily handy for gathering information and tracking down problems. While command line ping and trace utilities are bundled with the majority of operating systems, the utilities provided in DNS Expert are top-notch and include nice graphs and histograms where appropriate. Ping, for instance, provides a histogram view of packet timings along with a graphic of packet response times. As with any other good Ping tool, you can define the packet size in bytes and how many pings to try (including sending pings continuously, which in the wrong hands could create a Denial of Service attack).

DNS Query is fundamentally a user-friendly front end to NSLOOKUP; it makes very short work of checking specific zone DNS record data. Even better, you can right-click directly on any of the IP or DNS info returned by DNS Query, and perform an immediate Ping, DNS Query, DNS Analysis, or Trace route on the entry.

I found myself spending hours with DNS Query just poking around various domains to see how the servers and machines are arranged and configured. DNS Query's only shortcoming is that it can't directly print or save zone information. You have to first copy and then paste the info into another app, such as a text editor.

Rounding out the troika, Trace Route performs either a classic trace route diagnostic, or an improved version with the added benefits of neat scatterplot and average-value graphing along with fine tuning of trace settings.

In the end, what you don't know about DNS settings can definitely hurt you, and your customers. DNS Expert Pro won't replace having a hands-on, DNS-savvy staff member on board, but it will keep you from losing sleep if s/he jumps to another company.

Product Info:
DNS Expert Pro 1.5.1
Platforms: Windows 95/98, Windows NT, Mac OS
Price: $295
Vendor: Men and Mice

—End

return to the top of the article

Comments? Questions?
Drop a line to the Author or the Editors