> note that joe's example brings up the interface before starting the name > server program, and bringing it down if the name server program exits. > this presumes that the name server will start very quickly, and that while > running, it is healthy. since i've seen name server programs be unhealthy > while running, and/or take a long time to start, i'm now considering an > outboard shell script that runs some kind of DNS query and decides, based > on the result, whether to bring the dedicated loopback interface up or down.
All deference to this model, we've all seen these kinds of problems with name servers. We *can* be certain that bringing a loopback interface up or down takes almost no time (with the implied effect to a speaker like Quagga). There is *no* reason with a sufficiently deep name server depth (depends on your load) that your monitoring script should *need* to hurry to test this condition. Every 5-10 or even 15 minutes to see if its eligible to bring up, more frequently to see if its eligible to take down. This also reduces oscillation. This means, bring up/kill off your name server in one cronjob (automatically taking the interface down at the end or after a kill), and monitor/talk to the interface in another (up function and sometimes the down). You'll be much happier. Deepak Jain AiNET _______________________________________________ NANOG mailing list NANOG@nanog.org http://mailman.nanog.org/mailman/listinfo/nanog