/etc/hosts vs DNS & sendmail
Hi All,
I have a question about how /etc/hosts & DNS work on a solaris 9 box.
When I have entries in /etc/hosts that are not in DNS and I run say nslookup the utility will not find the ip. Put if I ping the entry in /etc/hosts it will find it. Basically I have a box with default sendmail and in /etc/hosts I have a entry with mailhost added to it at the end. nslookup does not find the box ping does and sendmail can't send mail to it and I can not verify that it ever worked correctly.
1) what is up with nslookup no seeing /etc/hosts?
2) can sendmail send to hosts per FQDN listed in /etc/hosts & use a DNS server at the same time?
thanks
-im
[699 byte] By [
@whata] at [2007-11-26 17:12:28]
# 1
> When I have entries in /etc/hosts that are not in DNS
> and I run say nslookup the utility will not find the
> ip.
Correct. nslookup and /etc/hosts are controlled by /etc/nsswitch.conf.
Files says to search /etc/hosts.
Anything else says to use that name service.
> Put if I ping the entry in /etc/hosts it will
> find it.
If it is in /etc/hosts and /etc/nsswitch.conf says to search /etc/hosts.
> and in /etc/hosts I have a entry with mailhost added
> to it at the end. nslookup does not find the box ping
> does and sendmail can't send mail to it and I can not
> verify that it ever worked correctly.
Sendmail can be compiled to use or disregard name server lookups in addition to the /etc/nsswitch.conf file.
sendmail -v e-mail_addr, should show you some basic diagnostics.
> 1) what is up with nslookup no seeing /etc/hosts?
That's the way it works.
> 2) can sendmail send to hosts per FQDN listed in
> /etc/hosts & use a DNS server at the same time?
sure, see /etc/nsswitch.conf and the sendmail compile time options.
http://www.ilkda.com/sendmail/
alan
# 2
> > When I have entries in /etc/hosts that are not in
> DNS
> > and I run say nslookup the utility will not find
> the
> > ip.
>
> Correct. nslookup and /etc/hosts are controlled by
> /etc/nsswitch.conf.
No. nslookup does not use /etc/nsswitch.conf.
nslookup is a DNS debugging tool and will always use DNS.
If you want a general host lookup tool that does follow the system libraries, use 'getent' instead.
--
Darren
# 3
> > > When I have entries in /etc/hosts that are not
> in
> > DNS
> > > and I run say nslookup the utility will not find
> > the
> > > ip.
> >
> > Correct. nslookup and /etc/hosts are controlled
> by
> > /etc/nsswitch.conf.
>
> No. nslookup does not use /etc/nsswitch.conf.
I should have stated that differently.
thanks,
alan
