Usually, when connecting, the ISP will provide you with their DNS server
addresses, and they'll be written into /etc/resolv.conf file by the
scripts that run when you're connecting, if they're not already there.
I've noticed that if the file doesn't need changing, it didn't get
changed (i.e. if I'd preloaded it with my ISP's DNS server IP addresses,
at the top of the list, they remained). But if it did need changing
(i.e. I had others, or local name server addresses first), the ISP's
would be written into it, and a backup of that file might be restored
after you disconnected.
Sorry I forgot to mention that I'm not using dial-up. I am using DSL.
My modem router is acting as DHCP server for rest of the network but
I have assigned the static address for my FC5 box because I am serving
a small wiki inside the LAN and planning to use it for public also
using DynDNS.
The problem with my other widnows machines unable to connect with my
FC5 box has something to do with the Samba since windows machines uses
NetBIOS names to locate the computer. So when my host name suddenly
changed without any notice, the wiki served from FC5 became unavilable
to windows.
On those notes: You don't usually need to do anything, it's done for
you automatically. If you add them while connected, then disconnect,
you might get a /etc/resolv.conf file that's different (as the backup
gets restored over your modifications). If you're going to add them
manually, it's better to do so while off-line.
In deference to your subject line, I have found some oddities with it as
well, particularly when I hadn't manually set up my machines local
addresses - it might add them (machine hostname and FQDN) to the
localhost line.
a command line, and see what you get). Or the address associated with
an interface (each interface has its own name). It may well be that
when you connect to your ISP you're supplied with a collection of
different details, which your machine may use:
* The ISP's DNS server numerical IP addresses.
* A gateway address that you connect through for internet traffic.
* A public numerical IP address for you, e.g. "192.0.34.166".
* A public named address for you, e.g. dialup166.example.com, of
which "dialup66" may be used as a temporary hostname for you,
and example.com as temporary domain name for you, by your PC.
* It's also possible to supply you with addresses to use for other
types of services, as well.
> My question is still remains:
> Does this utility just wipes out everything and rewrites without
> considering what is already been configured?
Actually "127.0.0.1 localhost.localdomain localhost" line was
there in my hosts file when I first installed FC5. After that I
changed my hostname, given static IP address, DNS lookup addresses
etc. through the graphical interface to something else like "zeeweb".
Now what happened was it removed the line
"127.0.0.1 localhost.localdomain localhost"
and replaced with my new setting.
"192.168.1.2 zeeweb"
As a result in next boot my "sendmail" and "sm_client" took forever to
boot trying to resolve the hostname. This is the problem I posted in:
https://www.redhat.com/archives/fedora-list/2006-July/msg01627.html
In the first place I didn't know that the first line was important to
make other programs function well (like sendmail, ... etc.). (Novice
like me will not know that. They simply rely on what easiest method
available and use it). The problem was solved by hand editing the
/etc/hosts file and adding the line back again. Now my etc host files
have two line and working well:
===================================
127.0.0.1 localhost.localdomain localhost
192.168.1.2 zeeweb.locallan.org zeeweb
===================================
After few days I changed my hostname (hand edited /etc/hosts file) and
now it looks like this:
===================================
127.0.0.1 localhost.localdomain localhost
192.168.1.2 zeenet.locallan.org zeenet
===================================
Few days ago my ISP's DNS went down and they gave me new set of DNS
look up addresses to use. Since I don't know which file contains the
DNS lookup addresses, I used the graphical interface this time to
change the DNS lookup address. After saving the setting and
reactivating the network, other windows mahcine on the LAN couldn't
reach my FC5 mahcine hosted wiki. I tried to figure out for long time
and found out that my hostname has changed back to the previous
setting. This time again I have to hand edit the /etc/hosts file and
change the host name and all is wokring well again.
So how do you explain this?
