I call this one the case of the non-redundant redundant MX; it's muchlike the first time except more thorough:

; sdig mx mumble.utoronto.ca.0 mail.mumble.utoronto.ca.0 jackson.mumble.utoronto.ca.5 mail.mumble.utoronto.ca.; sdig a mail.mumble.utoronto.ca.128.100.X.Y; sdig a jackson.mumble.utoronto.ca.128.1

Here's a not entirely hypothetical question: suppose that your machinesare coming up after a building-wide power outage, except that ascattering of them (on various different networks) are either not up ornot reachable. Could you look at what machines are failing to appear andidentify whether there's likely to be a switch that's failed, and if so,where that switch would be?

(This happened to us yesterday. There was some confusion, because guesswhat we don't have

We have a problem, and that problem is authentication. In a not uncommonpattern, we have a central set of core services, run by a core group;email, fileservers, the login servers, and so on. Then we have a bunchof other people who want to build various web applications, rangingfrom departmental things all the way down to graduate students puttingtogether projects.

Many of these web applications need accounts and authentication. Thenatural and best logins and passwords to use are people's existingdepartmental