Question

1. Which are the 4 main TCP/IP Configuration files?
2. Which is the role of the /etc/host file? In which occasions you may want to use it?
3. In which scenarios you may want to use the DNS server instead of the /etc/host file?
4. Which is the role of the /etc/services file? In which occasions you may want to edit/update it?
5. If you develop an application which uses port 5000 to communicate with the database, which is the entry that you need to add in the /etc/services file?
6. Which user is allowed to make changes to the /etc/services file?
7. Which is the role of the /etc/resolv.conf file?
8. Which is the relationship between the /etc/resolv.conf and the DNS server?
9. How many DNS servers can you define in the /etc/resolve.conf file?
10. What is a full qualified domain name?
11. Which is the role of the /etc/nsswitch.conf?
12. How do you force a server to use the host file to try to resolve a computer name first and then the DNS server?

Answer 1

Which is the role of the /etc/host file? In which occasions you may want to use it?
when you want to map or block any website you can map site with the ip address like shown below

127.0.0.1    www.yahoo.com

so if you have added this line to the hosts file yahoo will be redirected to the loopback ip within your system only

In which scenarios you may want to use the DNS server instead of the /etc/host file?
when system is not finding the route to the internet at that time DNS server need to be placed in between.

Which is the role of the /etc/services file? In which occasions you may want to edit/update it?
when we want to find that which services are running or is it installed or not at that time we need /etc/services

If you develop an application which uses port 5000 to communicate with the database, which is the entry that you need to add in the /etc/services file?

127.0.0.1:5000 www.website.com

Which user is allowed to make changes to the /etc/services file?
sudo or root user

Which is the role of the /etc/resolv.conf file?
resolv.conf is the name of a computer file used in various operating systems to configure the system's Domain Name System (DNS) resolver.

Which is the relationship between the /etc/resolv.conf and the DNS server?
The file is a plain-text file usually created by the network administrator or by applications that manage the configuration tasks of the system. when DNS servers are managed by the machines

How many DNS servers can you define in the /etc/resolve.conf file?
there is no limit

What is a full qualified domain name?
A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name

Which is the role of the /etc/nsswitch.conf?
The Name Service Switch (NSS) configuration file, /etc/nsswitch.conf, is used by the GNU C Library and certain other applications to determine the sources from which to obtain name-service information in a range of categories, and in what order. Each category of information is identified by a database name.

How do you force a server to use the host file to try to resolve a computer name first and then the DNS server?
by default it will check hosts file no need to force it

Thanks