Chapter 8 - Configuring Networks

Question 1

What are the two types of IP addresses available now?

Answer 1

IPv4 and IPv6

Question 2

What is an IPv4 address?

Answer 2

These are based on 32-bit addresses and have four octets, separated by dots, such as 192.168.10.100.

Question 3

What is an IPv6 address?

Answer 3

These are based on 128-bit addresses and are written in eight groups of hexadecimal numbers that are 16 bits each and separated by colons.
An IPv6 address may look like fe80:badb:abe01:45bc:34ad:1313:6723:8798.

Question 4

What is a host?

Answer 4

A host is typically a server providing services on the network

Question 5

How does computers commuinicate?

Answer 5

To make it easier for computers to communicate with one another, every IP address
belongs to a specific network, and to communicate with computers on another network,
a router is used

Question 6

What is a router?

Answer 6

A router is a machine (often dedicated hardware that has been created for that purpose) that connects networks to one another.

Question 7

What are private IP addresses?

Answer 7

Private network addresses are addresses that are for use in internal networks only. Some specific IP network addresses have been reserved for this purpose:

• 10.0.0.0/8 (a single Class A network)
• 172.16.0.0/12 (16 Class B networks)
• 192.168.0.0/16 (256 Class C networks)

Question 8

What is the length of MAC addresses?

Answer 8

12-byte MAC address

An example of a MAC address is 00:0c:29:7d:9b:17.

Question 9

What are the two parts of the MAC addresses?

Answer 9

The first 6 bytes is the vendor ID, and the second 6 bytes is the unique node ID

Question 10

How do the default names of network cards in RHEL8 begin?

Answer 10

1. Ethernet interfaces begin with en, WLAN interfaces begin with wl, and WWAN interfaces begin with ww.
2. The next part of the name represents the type of adapter.
3. Then follows a number, which is used to represent an index, ID, or port
4. If the fixed name cannot be determined, traditional names such as eth0 are used.

Question 11

Which command or utility can be used to check the configuration of network?

Answer 11

ip utility, or the ip command

Question 12

what is the command “ip addr” used for?

Answer 12

Use ip addr to configure and monitor network addresses

Question 13

What is the command “ip route” used for?

Answer 13

To configure and monitor routing information

Question 14

Which command is used to configure and monitor network link state?

Answer 14

ip link

Question 15

Which command to use to check or show current network settings?

Answer 15

ip addr show

Question 16

Which interface is used for communication between the processes and what is the default IP of the loopback interface in Linux?

Answer 16

The loopback interface is used for communication between processes. Some processes are using the IP protocol for internal communications. For that reason, you’ll always find a loopback interface, and the IP address of the loopback interface is always set
to 127.0.0.1

Question 17

What are all the informations seen in “ip addr show” command?

Answer 17

1. Current state
2. MAC address Configuration
3. IPv4 configuration
4. IPv6 Configuration

Question 18

Which command to use if you are just interested to see the link status of the network interfaces?

Answer 18

ip link show

Question 19

Which service in RHEL8 manages the networking?

Answer 19

NetworkManager service.
You can use the systemctl status NetworkManager
command to verify its current status

Question 20

For what purpose is the commands nmtui command or the nmcli command used for?

Answer 20

To manage the network connections that you want to assign to devices, you use the nmtui command or the
nmcli command.

Question 21

Which command to use to check your current permissions with changing/modifying the network configuration?

Answer 21

nmcli gen permissions

Question 22

Which command can be used to temporarily set IP address on a network interface?

Answer 22

ip addr add

Question 23

How to use nmcli command to show all connections?

Answer 23

nmcli con show
This shows active and inactive connections. You can easily see the difference because inactive connections are not currently assigned to a device

Question 24

How to see all the properties of the network interface ens33?

Answer 24

nmcli con show ens33

syntax is : nmcli con show

Question 25

What is the difference between a connection and a device?

Answer 25

A device is a network interface card. A connection is the configuration that is used on a device. nmcli con show nmcli dev status

Question 26

What command is a text user interface that allows you to create network connections easily?

Answer 26

nmtui

Question 27

How to use the nmcli command to modify an existing setting?

Answer 27

nmcli con mod

Question 28

What are the menu options in nmtui interface?

Answer 28

1. Edit a Connection 2. Activate a Connection 3. Set System Hostname

Question 29

Every network connection that you create is stored in a network configuration file. Where is this file present?

Answer 29

/etc/sysconfig/network-scripts

Question 30

How to identify the names of network configuration files?

Answer 30

The name of the configuration files starts with ifcfg- and is followed by the name of the network interface.

Question 31

Why is hostname necessary?

Answer 31

To communicate with the other hosts. Makes it more readable than IP addresses.

Question 32

What are the different parts in a hostname?

Answer 32

Hostname typically consists of different parts. These are the name of the host and the DNS domain in which the host resides. These two parts together make up for the fully qualified domain name (FQDN), which looks like server1.example.com

Question 33

What is FQDN?

Answer 33

Fully qualified domain name (FQDN) It is the name of the host and the DNS domain in which the host resides all together

Question 34

What are the different ways to change the hostname in linux?

Answer 34

1. Use nmtui and select the option Change Hostname. 2. Use hostnamectl set-hostname command 3. Edit the contents of the configuration file /etc/hostname.

Question 35

Give an example of setting hostname using hostnamectl command?

Answer 35

hostnamectl set-hostname myhost.example.com

Question 36

Which command to use to check the current hostname?

Answer 36

hostnamectl status

Question 37

What are the two columns in /etc/hosts file?

Answer 37

The first column has the IP address of the specific host, and the second column specifies the hostname.

Question 38

In which configuration file is the DNS information stored in ?

Answer 38

The NetworkManager configuration stores the DNS information in the configuration file for the network connection, which is in /etc/sysconfig/network-scripts, and from there pushes the configuration to the /etc/resolv.conf file, which is used for DNS name server resolving. Do not edit /etc/resolv.conf directly, as it will be overwritten the next time you restart NetworkManager.

Question 39

What are the different ways to set the DNS server?

Answer 39

1. Use nmtui to set the DNS name servers. 2. Set the DNS1 and DNS2 parameters in the ifcfg network connection configuration file in /etc/sysconfig/network-scripts. 3. Use a DHCP server that is configured to hand out the address of the DNS name server 4. Use nmcli con mod [+]ipv4.dns.dns

Question 40

if your computer is configured to get the network configuration from a DHCP server, the DNS server is also set via the DHCP server. If you do not want this to happen what should you do?

Answer 40

]1. Edit the ifcfg configuration file to include the option PEERDNS=no. or 2. Use nmcli con mod ipv4.ignore-auto-dns yes.