Scyld and resolv library

Dave Johnson ddj at
Thu Mar 8 06:28:30 PST 2001

One more thing that may bite bproc users/admins is the need for
/etc/protocols if an application uses getproto{ent,byname,bynumber},
and possibly /etc/services to support getserv{ent,byname,bynumber}.
I ran into this when running some of the netpipe benchmarks, which
uses getprotobyname.

Since the default behavior of nsswitch is to look in nis, then check
the appropriate file in /etc if nis fails to respond, you don't have
to change /etc/nsswitch.conf to get it to look at the /etc/protocols,
services, networks, ethers, etc.

	-- ddj

	Dave Johnson
	Brown University TCASCV
	ddj at

On Thu, Mar 08, 2001 at 05:27:13AM -0800, Jag wrote:
> On Thu, 08 Mar 2001, Carlos J. García Orellana wrote:
> > Hello,
> > 
> > I'm trying to start DNS resolver in nodes.
> > I've created a hosts, host.conf and resolv.conf files in nodes, but, DNS
> > doesn't work.
> > 
> > Not even, names in hosts file can be resolutes.
> It's debatable wether letting nodes do this resolving is the 'right
> thing', however I will assume that you have an application that's messed
> up enough that it needs it.
> By default, Scyld slave nodes have their nsswitch.conf setup so that
> they only do host lookups through beonss (referenced as 'bproc' in the
> nsswitch.conf).  This will resolve 'master' to the internal ip of the
> master node, 'self' to get your own IP, '.-1' to get the master node
> again, '.0' to get node zero, '.1' to get node one, and so on.  It also
> reverses these so that the ip of a node (or the master node's internal
> IP address) will resolve to '.<node number>' like above.   If you're
> just wanting smiliar functionality to this, then you don't have to worry
> about setting up dns and the hosts file.
> If you're wanting more than this, you're talking about things that
> theorectically shouldn't be on a beowulf cluster (like ipmasq on the
> head node to get out).  However, for the /etc/hosts and dns resolution,
> I'll tell you that the file you need to also look at is
> /etc/nsswitch.conf
> Jag

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