On Tue, Jun 1, 2010 at 3:55 PM, David Lum <david....@nwea.org> wrote: > Which brings up a question as I've had this debate with > my network architect. He says when monitoring servers to > ping by IP instead of hostname "in case DNS goes down". My > point is you should be testing for that infrastructure anyway so > ping by name doesn't get triggered unless DNS functionality (also > tested for) is working.
Generally speaking, I would prefer ping by name, simply so that when IP addresses or network numbers change, you don't have to manually update your monitoring system. Setting that problem aside, I would prefer two tests: One to test name resolution of that particular host's name (perhaps in multiple forms), and one to ping by IP address. That gives you more granularity in your monitoring system. One tells you when name resolution for that particular host is screwed up; the other tests connectivity and the ability of the host to return packets. Knowing *which* is down is more data than knowing "one or both is down". (I guess my ideal monitoring system would internally cache name lookups so that it could intelligently try the last known IP address if DNS is down, but one could argue that would be a rather severe case of creeping featureism.) > I'm of the "test as you operate" ... I generally agree. However, I expect your operations do not consist of pinging the host. The users are actually connecting to HTTP or SMB or SMTP or whatever. Ping is a synthetic test, and very different from the real thing. I've had boxes which were responding to ping be otherwise crashed to the point of needing a hardware reset. So I would be less inclined to worry about that aspect for a ping test (provided you are testing name resolution as well). Certainly, pinging by IP address without also monitoring name resolution means you will miss name resolution problems. -- Ben ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
