From: lew.pitcher@digitalfreehold.ca   
      
   On Thu, 29 Feb 2024 22:36:59 -0400, Mike Spencer wrote:   
      
   > Not limited to Slackware but as a long-time Slackware user, this group   
   > seems more like home to me...   
   >   
   > Given sendmail 8.17.1 running as daemon:   
   >   
   >      /usr/sbin/sendmail -L sm-mta -bd -q25m   
   >      /usr/sbin/sendmail -L sm-msp-queue -Ac -q25m   
   >   
   > is there a way to query the daemon to learn what nameserver(s) it is   
   > using?   
   [snip]   
   > My usual setup is a desktop cabled to a router that is in turn cabled   
   > to a gateway device using ISP "A".   
   >   
   > The sendmail daemon's only task is to deliver outgoing mail to a   
   > smarthost with TLS and AUTH.   
   >   
   > At times, using wicd, I disconnect from the router and reconnect via   
   > wi-fi, using a cell phone served by ISP "B" as an access point.  Wicd   
   > replaces /etc/resolv.conf with one that references the nameservers of   
   > ISP "B".  Apps such as a web browser and Usenet news proceed as   
   > expected after the change but sendmail fails to deliver messages to   
   > the remote smarthost.   
   >   
   > Restarting sendmail fixes this.   
   [snip]   
      
   I think that you are trying to solve the wrong problem. The problem isn't   
   that sendmail caches the address of the DNS server, but that you are   
   using a DNS server who's address may change over time.   
      
   You could just run a caching nameserver on your slackware box, and   
   resolve /all/ DNS queries against that server. This way, the DNS   
   server maintains a fixed address (perhaps, "localhost", in your case)   
   and sendmail doesn't have to fish about for DNS resolution.   
      
   A caching DNS server adds very little to the system overhead, and,   
   beyond the initial setup, needs little or no maintenance. It gives   
   the added benefit of adding a bit more security to your DNS queries,   
   in that your ISP /does not/ handle the queries,  /can't/ log or track   
   them, and /can't/ substitute their own sponsored/edited/redirected   
   answers.   
      
   --   
   Lew Pitcher   
   "In Skills We Trust"   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)