Whilst we humans like to give names to things, computers really like
numbers. On a TCP/IP network (which is what the Internet is), we call
machines by a particular name - and every machine lives in a
particular dquot;domaindquot;. For example, my
Linux workstation is called archenland and it resides in the
hedland.edu.au domain. Its human readable address is thus
archenland.hedland.edu.au. In order for this machine to be findable by
other computers on the Internet, it is actually known by its IP number.
Translating (resolving) machine (and domain) names into the numbers actually used on the Internet is the business of machines that offer the Domain Name Service.
When you make a PPP connection, you need to tell your Linux machine where it can get host name to IP number (address resolution) information so that you can use the machine names but your computer can translate these to the IP numbers it needs to work.
One way is to enter every host that you want to talk to into the /etc/hosts file (which is in reality totally impossible if you are connecting to the Internet); another is to use the machine IP numbers as opposed to the names (an impossible memory task for all but the smallest LANs).
The best way is to set up Linux so that it knows where to go to get this name to number information - automatically. This service is provided by the Domain Name Server system. All that is necessary is to enter the IP numbers in your /etc/resolv.conf file.
Your PPP server sysadmin/user support people should provide you with two DNS IP numbers (only one is necessary - but two gives some redundancy in the event of failure).
Your /etc/resolv.conf should look something like :-
domain your.isp.domain.name nameserver 10.25.0.1 nameserver 10.25.1.2
Edit this file (creating it if necessary) to represent the information that your ISP has provided. It should have ownership and permissions as follows :-
-rw-r--r-- 1 root root 73 Feb 19 01:46 /etc/resolv.conf
If you have already set up a /etc/resolv.conf because you are on a LAN, simply add the IP numbers of the PPP DNS servers to your existing file.