I don't think it's such a problem as it used to be, when the hostname was actually compiled into the kernel :) But even now, you can get into a mess with double host resolution, e.g. hvaing systems trying to look up
host.example.com.exmample.com etc. It's a fragile act dealing with multiple systems without normalization. >From a coding perspective, domain names are a pain. Because (as we have battled about before on the list) it is actually impossible to discover the domain name of a host without an explicit delcaration of it. So code that tries to append the domain name to hostnames for lookup has to make an educated guess - which it sometimes gets wrong. M On Mon, 2005-11-07 at 11:07 -0800, David Masterson wrote: > Mark Burgess wrote: > > On Sun, 2005-11-06 at 14:47 -0800, David Masterson wrote: > >> Mark Burgess wrote: > >>>> Regarding short_hostname, on my system '/bin/hostname' returns the > >>>> FQDN. If I try using $(host), I just get the FQDN. Is that normal? > >>>> That's why I'm using my own variable. > >>> > >>> This is normal if you have fully qualified names returned by your > >>> hostname lookup, which is not something I recommend. > >> > >> There is a discussion going on here about the merits of FQDN vs. > >> simple hostname. Would you care to elaborate on your reasons for > >> not recommending FQDN in hostname lookup? > >> > > > > Just as a matter of principle that you don't mix different kinds of > > information. It is the principle of "normalization" or "normal forms" > > in database theory. The hostname is one item of information, the > > domain name is another. You should be able to change and manage them > > independently of one another. If you always store the domain name as > > the host identity then you have made it very hard to separate those > > two pieces of information, and have made relative information > > absolute. > > It is also possible to record information that is incorrect and does > > not match information in DNS this way. Again. normalization says this > > is a bad idea. > > Hmm. I'm in the simple hostname camp, but IT is more in the FQDN camp. I > need to bring your explanation down a little -- can you give an example of > where FQDN caused problems? Is it just an esoteric "ease of use" issue or > does it have consequences? > > Consider establishing a company policy where all NIS servers are "nis[0-9]". > At the company level, these systems have an FQDN of "nis[0-9].x.com". > However, group NIS servers have an FQDN of "nis[0-9].y.x.com" (where y is the > group). Obviously, you could have multiple "nis1" hosts in your > organization. Is this a good company policy? > _______________________________________________ Help-cfengine mailing list Help-cfengine@gnu.org http://lists.gnu.org/mailman/listinfo/help-cfengine
