DNS Resolver Library - Quiz Explanation
The correct answers are indicated below, along with text that explains the correct answers.
1.
What is the function of the DNS resolver library?
Please select the best answer.
A.
To set a default gateway for the system
B.
To convert host names to IP addresses
C.
To convert IP addresses to host names
D.
To configure the network interface
The correct answer is B.
The function of the DNS resolver library is to convert host names to IP addresses. The resolver library is a package of subroutines, usually implemented as a shared-object library. It does one of three things: it looks up the IP address in a local database file, looks up the address in an NIS or NIS+ database, or looks up an address using DNS.
2.
Where is the basic configuration information for the DNS part of the resolver library stored?
Please select the best answer.
A.
In the /etc/resolv.conf configuration file
B.
In the /etc/hosts file
C.
In the /etc/nsswitch.conf file
D.
In the /etc/hostname.hme() file
The correct answer is A.
The basic configuration information for the DNS part of the resolver library is stored in the /etc/resolv.conf configuration file. This file contains the addresses of your DNS domain, and of up to three DNS servers.
The hosts file is often used by the resolver library to resolve host names to IP addresses.
3.
Which command would you use to display the results of the kernel's initial hardware probe?
Please select the best answer.
A.
ping
B.
dmesg
C.
ifconfig
D.
route
The correct answer is B.
The command you would use to display the results of the kernel's initial hardware probe is
dmesg
.
Two important pieces of information in the command's results are the interface name and the ethernet address.
4.
What command would you use to configure a network interface?
Please select the best answer.
A.
ping
B.
dmesg
C.
ifconfig
D.
route
The correct answer is C.
The command you would use to configure a network interface is
ifconfig
. The
ifconfig
command's three purposes are to list configured interfaces, to bring interfaces up and down, and to set the IP address and netmask.
5.
What is the difference between static routing and dynamic routing?
Please select the best answer.
A.
In static routing, information is programmed into the machine at boot time, whereas in dynamic routing, a route daemon communicates with other routing daemons to update the information in response to changing conditions.
B.
In dynamic routing, information is programmed into the machine at boot time, whereas in static routing, a route daemon communicates with other routing daemons to update the information in response to changing conditions.
C.
Dynamic routing involves the use of the ARP cache, whereas dynamic routing involves the use of routing tables.
D.
Static routing is where the system communicates on the local network, using information programmed in at boot time, and dynamic routing involves the use of routing tables.
The correct answer is A.
The difference between static routing and dynamic routing is that in static routing, information is programmed into the machine at boot time, whereas in dynamic routing, a route daemon communicates with other routing daemons to update the information in response to changing conditions. Routing is controlled by a routing table, which is maintained by the kernel.
6.
What are two possible sources where a host can configure its name?
Please select the best answer.
A.
The
uname
command and the
hostname
command
B.
The
uname
command and the name service
C.
The
hostname
command and the name service
D.
The
uname
command and the
arp
command
The correct answer is C.
The two possible sources where a host can configure its name are the
hostname
command and the name service. The name service includes the local /etc/hosts file, the NIS and NIS+ service, and the DNS server.
7.
What is the function of the nsswitch.conf file?
Please select the best answer.
A.
To resolve IP addresses to ethernet addresses
B.
To tell the resolver library which of three possible methods to use to convert host names to IP addresses and back
C.
To configure the network interface by joining the link-layer portion of the protocol stack to the network layer
D.
To tell the system where to send information meant for machines not on the local network
The correct answer is B.
The function of the nsswitch.conf file is to tell the resolver library which of three possible methods to use to convert host names to IP addresses and back. The nsswitch.conf file contains a line telling the resolver library to look first in the /etc/hosts file, then try to contact an NIS+ server, then an NIS server, and finally, to try the Domain Name Service.