Why does rpc.lockd(8) and rpc.stat(8) require a working Internet connection

[Alan Somers]

On Fri, Sep 8, 2017 at 3:03 AM, Aryeh Friedman <aryeh.friedman at gmail.com> wrote:
> My cable modem was out for a few hours last night and my NFS based *LOCAL*
> (same subnet [192.168.11.XXX] and physical LAN) file server started
> glitching up on attempting to contact lockd and statd on the server from
> the client(s) saying that the service was non-responsive and/or the server
> couldn't be found.   I attempted to switch over to /etc/hosts based host
> resolution to no avail.   I also tried switching to purely IP addr based
> connections to no avail.   Note NIS/YP kept working.
>
> Several questions:
>
> 1. How do I make it so I can completely disconnect my LAN from the rest of
> the Internet and not have NFS fail like this
>
> 2. Why does NFS require a live internet connection?
>
> --
> Aryeh M. Friedman, Lead Developer, http://www.PetiteCloud.org

My guess would be DNS.  If your cable _modem_ (not just connection)
was out, and your machines are configured to use the cable modem as
their DNS server, and rpc.statd tried to do a reverse DNS lookup of
your client's IP address, then that might cause it to hang.  Using
/etc/hosts was a sensible move.  Perhaps you accidentally left out an
address?  If it happens again you could use tcpdump to see if anything
is trying to contact the cable modem's DNS port.

-Alan