Advice on networking?

[martin at molndal.ericsson.se]

Hi: This is a request for some advice regarding networking (I just hope
this is the correct forum for this....).  I applogize beforehand for the
vague questions.  I naturally don't expect full tutorials on the subjects,
but would appreciate some advice and pointers to get me started in the
correct direction(s).  Please note me also, if the questions below doesn't
belong here.

1) I'm going to use the file /etc/netgroup for different purposes (e.g. in
   /etc/exports), and wonder if I need to specify domain name in the
   "triplets"?  Under what circumstances is it necessary (security wise) to
   specify the domain name.  Always?  I will use netgroup simply to define
   groups of machines (never specify users).  I run YP, am connected to
   another net (different YP) via a router (that's what makes me think I need
   to specify domain name).

2) The term "domain" seems to me be used for several different purposes.
   I've used it to mean "internet domain".  Is this the same as YP domain?
   How does this relate to mail domain (I guess sendmail fixes that, if
   specified in sendmail.cf??)?

3) What is the /etc/networks file used for (which utilities read it, or
   corresponding YP map)?  What is a "network" in this context?

Ok, I realize that I need to do some studying about networking, but the
amount of information seems so enormous (doesn't it always?!) right now.
Any, and all, advice/comment is appreciated.

Martin Fredriksson (G/TTH)	| Internet: <martin at molndal.ericsson.se>
System Admin Sun/Unix		|
Ericsson Radar Electronics AB	| Phone:	+46 31 671036
S-431 84  MOLNDAL, SWEDEN	| Fax:		+46 31 876639