Regedit vs Regedt32

Here is a decent article from Microsoft explaining "The Differences between Regedit.exe and Regedt32.exe": http://support.microsoft.com/kb/141377 .

I would highlight that when using Windows 2000 Server, you want to use Regedt32.
While the String Editor (associated with file type REG_SZ) appears to operate the same using either executable, the Multi-String Editor (associated with file type REG_MULTI_SZ) functions properly only if Regedt32 is used.

The Microsoft article warns that "If you try to edit either of these data types (REG_MULTI_SZ or REG_EXPAND_SZ), Regedit.exe saves it as REG_SZ, and the data type no longer performs its intended function."

Forward Confirmed reverse DNS

I read this article on wikipedia: http://en.wikipedia.org/wiki/Forward_Confirmed_reverse_DNS.

There, I found this tool:
http://ipadmin.junkemailfilter.com/rdns.php.

In my email account, I then select a message and right-click and choose "View message source."
About the fifth line down, I see the IP address that the message was received from.
I can then plug that IP into the tool above and validate it.