On Wed, Mar 24, 2021 at 02:44:37PM -0700, Charlie Gibbs wrote: > I tried removing the 192.168.0.1 line along with the "search telus" > line. I didn't notice any difference, but could this be because > this stuff is buffered somewhere? Perhaps I need to kick something > to make sure the new file is read.
Well, that depends entirely on what tests you performed, and what applications you're using (the real reason why you were testing these things in the first place). A typical test would involve you running shell commands to perform name lookups. Each of those commands would invoke a new process, which would re-read nsswitch.conf and resolv.conf and so on. In that sense, there is nothing you need to "restart". The restarting is implicit in the fact that you are running shell commands, each one containing a separate, standalone instance of the resolver. If there is an already-running process that you were using to do real-life stuff (e.g. a web browser), and you wanted to load a new page in the already-running instance of your web browser, then the web browser, which has its own separate, standalone instance of the resolver (possibly even a *unique* resolver, because browsers are special snowflakes), may have cached some information, such as the contents of resolv.conf. Thus, you would be well-advised to restart any running browsers, mail transport agents, NFS servers, and so on. Any or all of these programs that use DNS results may have cached the old resolv.conf, or the old results from DNS (positive and negative), or all of the above. But it all starts with an actual testing methodology of some kind, and the transparent reporting of your testing results. "I didn't notice any difference" is not that.
