Wednesday, 9 December 2020

RHCSA exam preparation


Exam A



QUESTION 1



SIMULATION



Configure your Host Name, IP Address, Gateway and DNS.

Host name: station.domain40.example.com

/etc/sysconfig/network

hostname=abc.com

hostname abc.com

IP Address:172.24.40.40/24

Gateway172.24.40.1

DNS:172.24.40.1





Explanation: # cd /etc/syscofig/network‐scripts/

# ls

# vim ifcfg‐eth0 (Configure IP Address, Gateway and DNS) IPADDR=172.24.40.40

GATEWAY=172.24.40.1

DNS1=172.24.40.1

# vim /etc/sysconfig/network

(Configure Host Name)

HOSTNAME= station.domain40.example.com

OR

Graphical Interfaces:

System‐>Preference‐>Network Connections (Configure IP Address, Gateway and DNS) Vim /etc/sysconfig/

network

(Configure Host Name)




QUESTION 2



SIMULATION

Add 3 users: harry, natasha, tom.

The requirements: The Additional group of the two users: harry, Natasha is the admin group. The user: tom's

login shell should be non‐interactive.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # useradd ‐G admin harry

# useradd ‐G admin natasha

# useradd ‐s /sbin/nologin tom

# id harry;id Natasha (Show additional group)

# cat /etc/passwd

(Show the login shell)

OR

# system‐config‐users

 




QUESTION 3



SIMULATION

Create a catalog under /home named admins. Its respective group is requested to be the admin group. The

group users could read and write, while other users are not allowed to access it. The files created by users

from the same group should also be the admin group.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # cd /home/

# mkdir admins /

# chown .admin admins/

# chmod 770 admins/

# chmod g+s admins/



QUESTION 4



SIMULATION

Configure a task: plan to run echo hello command at 14:23 every day.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # which echo

# crontab ‐e

23 14 * * * /bin/echo hello

# crontab ‐l (Verify)



QUESTION 5



SIMULATION

Find the files owned by harry, and copy it to catalog: /opt/dir

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # cd /opt/

# mkdir dir

# find / ‐user harry ‐exec cp ‐rfp {} /opt/dir/ \;




QUESTION 6

SIMULATION

Find the rows that contain abcde from file /etc/testfile, and write it to the file/tmp/testfile, and the sequence is

requested as the same as /etc/testfile.

Answer: See explanation below.

Explanation

Explanation/Reference:


Explanation: # cat /etc/testfile | while read line;

do

echo $line | grep abcde | tee ‐a /tmp/testfile

done

OR

grep `abcde' /etc/testfile > /tmp/testfile



QUESTION 7



SIMULATION


Create a 2G swap partition which take effect automatically at boot‐start, and it should not affect the original

swap partition.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # fdisk /dev/sda

p

(check Partition table)

n

(create new partition: press e to create extended partition, press p to create the main partition, and the

extended partition is further divided into logical partitions) Enter

+2G

t

l

W

partx ‐a /dev/sda

partprobe

mkswap /dev/sda8

Copy UUID

swapon ‐a

vim /etc/fstab

UUID=XXXXX swap swap defaults 0 0

(swapon ‐s)



QUESTION 8

SIMULATION



Create a user named alex, and the user id should be 1234, and the password should be alex111.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # useradd ‐u 1234 alex

# passwd alex

alex111

alex111

OR

echo alex111|passwd ‐stdin alex

 



QUESTION 9


SIMULATION

Install a FTP server, and request to anonymous download from /var/ftp/pub catalog. (it needs you to configure

yum direct to the already existing file server.)

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # cd /etc/yum.repos.d

# vim local.repo

[local]

name=local.repo

baseurl=file:///mnt

enabled=1

gpgcheck=0

# yum makecache

# yum install ‐y vsftpd

# service vsftpd restart

# chkconfig vsftpd on

# chkconfig ‐‐list vsftpd

# vim /etc/vsftpd/vsftpd.conf

anonymous_enable=YES



QUESTION 10



SIMULATION



Configure a HTTP server, which can be accessed through http://station.domain40.example.com.

Please download the released page from http://ip/dir/example.html.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # yum install ‐y httpd

# chkconfig httpd on

# cd /var/www/html

# wget http://ip/dir/example.html

# cp example.com index.html

# vim /etc/httpd/conf/httpd.conf

NameVirtualHost 192.168.0.254:80

<VirtualHost 192.168.0.254:80>

DocumentRoot /var/www/html/

ServerName station.domain40.example.com

</VirtualHost>


QUESTION 11

SIMULATION

Configure the verification mode of your host account and the password as LDAP. And it can login successfully

through ldapuser40. The password is set as "password". And the certificate can be downloaded from http://ip/

dir/ldap.crt. After the user logs on the user has no host directory unless you configure the autofs in the

following questions.

 

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: system‐config‐authentication

LDAP Server: ldap//instructor.example.com (In domain form, not write IP)

OR

# yum groupinstall directory‐client (1.krb5‐workstation 2.pam‐krb5 3.sssd)

# system‐config‐authentication

1.User Account Database: LDAP

2.LDAP Search Base DN: dc=example,dc=com

3.LDAP Server: ldap://instructor.example.com (In domain form, not write IP) 4.Download CA Certificate

5.Authentication Method: LDAP password

6.Apply

getent passwd ldapuser40

QUESTION 12

SIMULATION

Configure autofs to make sure after login successfully, it has the home directory autofs, which is shared as /

rhome/ldapuser40 at the ip: 172.24.40.10. and it also requires that, other ldap users can use the home

directory normally.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # chkconfig autofs on

# cd /etc/

# vim /etc/auto.master

/rhome /etc/auto.ldap

# cp auto.misc auto.ldap

# vim auto.ladp

ldapuser40 ‐rw,soft,intr 172.24.40.10:/rhome/ldapuser40

* ‐rw,soft,intr 172.16.40.10:/rhome/&

# service autofs stop

# server autofs start

# showmount ‐e 172.24.40.10

# su ‐ ladpuser40

QUESTION 13

SIMULATION

Configure the system synchronous as 172.24.40.10.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: Graphical Interfaces:

System‐‐>Administration‐‐>Date & Time


# system‐config‐date

QUESTION 14

SIMULATION

Change the logical volume capacity named vo from 190M to 300M. and the size of the floating range should

set between 280 and 320. (This logical volume has been mounted in advance.)

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # vgdisplay

(Check the capacity of vg, if the capacity is not enough, need to create pv , vgextend , lvextend)

# lvdisplay (Check lv)

# lvextend ‐L +110M /dev/vg2/lv2

# resize2fs /dev/vg2/lv2

mount ‐a

(Verify)

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 

(Decrease lvm)

# umount /media

# fsck ‐f /dev/vg2/lv2

# resize2fs ‐f /dev/vg2/lv2 100M

# lvreduce ‐L 100M /dev/vg2/lv2

# mount ‐a

# lvdisplay (Verify)

OR

# e2fsck ‐f /dev/vg1/lvm02

# resize2fs ‐f /dev/vg1/lvm02

# mount /dev/vg1/lvm01 /mnt

# lvreduce ‐L 1G ‐n /dev/vg1/lvm02

# lvdisplay (Verify)



QUESTION 15

SIMULATION

Create a volume group, and set 16M as a extends. And divided a volume group containing 50 extends on

volume group lv, make it as ext4 file system, and mounted automatically under /mnt/data.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # pvcreate /dev/sda7 /dev/sda8

# vgcreate ‐s 16M vg1 /dev/sda7 /dev/sda8

# lvcreate ‐l 50 ‐n lvm02

# mkfs.ext4 /dev/vg1/lvm02

# blkid /dev/vg1/lv1

# vim /etc/fstab

# mkdir ‐p /mnt/data

UUID=xxxxxxxx /mnt/data ext4 defaults 0 0

# vim /etc/fstab

# mount ‐a

# mount

(Verify)

QUESTION 16

SIMULATION

Upgrading the kernel as 2.6.36.7.1, and configure the system to Start the default kernel, keep the old kernel

available.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # cat /etc/grub.conf

# cd /boot

# lftp it

# get dr/dom/kernel‐xxxx.rpm

# rpm ‐ivh kernel‐xxxx.rpm

# vim /etc/grub.conf

default=0



QUESTION 17

SIMULATION

Create a 512M partition, make it as ext4 file system, mounted automatically under /mnt/data and which take

effect automatically at boot‐start.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # fdisk /dev/vda

n

+512M

w

# partprobe /dev/vda

# mkfs ‐t ext4 /dev/vda5

# mkdir ‐p /data

# vim /etc/fstab

/dev/vda5 /data ext4 defaults 0 0

# mount ‐a



QUESTION 18

SIMULATION

Create a volume group, and set 8M as a extends. Divided a volume group containing 50 extends on volume

group lv (lvshare), make it as ext4 file system, and mounted automatically under /mnt/data. And the size of the

floating range should set between 380M and 400M.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # fdisk

# partprobe

# pvcreate /dev/vda6

# vgcreate ‐s 8M vg1 /dev/vda6 ‐s

# lvcreate ‐n lvshare ‐l 50 vg1 ‐l

# mkfs.ext4 /dev/vg1/lvshare

# mkdir ‐p /mnt/data

# vim /etc/fstab

/dev/vg1/lvshare /mnt/data ext4 defaults 0 0

# mount ‐a

# df ‐h



QUESTION 19

SIMULATION

Download ftp://192.168.0.254/pub/boot.iso to /root, and mounted automatically under /media/cdrom and which

take effect automatically at boot‐start.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # cd /root; wget ftp://192.168.0.254/pub/boot.iso

# mkdir ‐p /media/cdrom

# vim /etc/fstab

/root/boot.iso /media/cdrom iso9660 defaults,loop 0 0

# mount ‐a

mount [‐t vfstype] [‐o options] device dir

QUESTION 20

SIMULATION

Add admin group and set gid=600

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # groupadd ‐g 600 admin

QUESTION 21

SIMULATION

Add user: user1, set uid=601

Password: redhat

The user's login shell should be non‐interactive.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # useradd ‐u 601 ‐s /sbin/nologin user1

# passwd user1

redhat



QUESTION 22

SIMULATION

Add users: user2, user3.

The Additional group of the two users: user2, user3 is the admin group Password: redhat

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # useradd ‐G admin user2

# useradd ‐G admin user3

# passwd user2

redhat

# passwd user3

redhat



QUESTION 23

SIMULATION

Copy /etc/fstab to /var/tmp name admin, the user1 could read, write and modify it, while user2 without any

permission.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: # cp /etc/fstab /var/tmp/

# chgrp admin /var/tmp/fstab

# setfacl ‐m u:user1:rwx /var/tmp/fstab

# setfacl ‐m u:user2:‐‐‐ /var/tmp/fstab

# ls ‐l

‐rw‐rw‐r‐‐+ 1 root admin 685 Nov 10 15:29 /var/tmp/fstab



QUESTION 24

SIMULATION

Configure a task: plan to run echo "file" command at 14:23 every day.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: (a) Created as administrator

# crontab ‐u natasha ‐e

23 14 * * * /bin/echo "file"

(b)Created as natasha

# su ‐ natasha

$ crontab ‐e

23 14 * * * /bin/echo "file"



QUESTION 25

SIMULATION

Configure a default software repository for your system.

One YUM has already provided to configure your system on http://server.domain11.example.com/pub/ x86_64/


Server, and can be used normally.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: Yum‐config‐manager ‐‐add‐repo=http://content.example.com/rhel7.0/x86‐64/dvd” is to generate a

file vim content.example.com_rhel7.0_x86_64_dvd.repo, Add a line gpgcheck=0

Yumcleanall

Yumrepolist

Almost 4305 packages are right, Wrong Yum Configuration will lead to some following questions cannot be

worked out.



QUESTION 26

SIMULATION

Adjust the size of the Logical Volume.

Adjust the size of the vo Logical Volume, its file system size should be 290M. Make sure that the content of

this system is complete.

Note: the partition size is rarely accurate to the same size as required, so in the range 270M to 320M is

acceptable.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: Addition

df ‐hT

lvextend ‐L +100M /dev/vg0/vo

Lvscan

xfs_growfs /home/ //home is the mounted directory of the LVM, this step just need to do in the practice

environment, and test EXT4 does not need this step.

resize2fs /dev/vg0/vo// use this command to update in examination.

df ‐hT

OR

Subtraction

e2fsck ‐f/dev/vg0/vo

umount /home

resize2fs /dev/vg0/vo // the final required partition capacity is 100M lvreduce ‐l 100M /dev/vg0/vo

mount /dev/vg0/vo/home

df ‐hT



QUESTION 27

SIMULATION

Create User Account.

Create the following user, group and group membership:

Adminuser group

User natasha, using adminuser as a sub group

User Harry, also using adminuser as a sub group

User sarah, can not access the SHELL which is interactive in the system, and is not a member of adminuser,

natashaharrysarah password is redhat.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: groupadd adminuser

useradd natasha ‐G adminuser

useradd haryy ‐G adminuser

useradd sarah ‐s /sbin/nologin

Passwd user name // to modify password or echo redhat | passwd ‐‐stdin user name id natasha // to view user

group.




QUESTION 28

SIMULATION

Configure /var/tmp/fstab Permission.

Copy the file /etc/fstab to /var/tmp/fstab. Configure var/tmp/fstab permissions as the following:

Owner of the file /var/tmp/fstab is Root, belongs to group root

File /var/tmp/fstab cannot be executed by any user

User natasha can read and write /var/tmp/fstab

User harry cannot read and write /var/tmp/fstab

All other users (present and future) can read var/tmp/fstab.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: cp /etc/fstab /var/tmp/

/var/tmp/fstab view the owner setfacl ‐m u:natasha:rw‐ /var/tmp/fstab setfacl ‐m u:haryy:‐‐‐ /var/tmp/fstab

Use getfacl /var/tmp/fstab to view permissions



QUESTION 29

SIMULATION

Configure a cron Task.

User natasha must configure a cron job, local time 14:23 runs and executes: */bin/echo hiya every day.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: crontab –e –u natasha

23 14/bin/echo hiya

crontab ‐l ‐u natasha // view

systemctlenable crond

systemcdlrestart crond

QUESTION 30

SIMULATION

Create a Shared Directory.

Create a shared directory /home/admins, make it has the following characteristics:

/home/admins belongs to group adminuser

This directory can be read and written by members of group adminuser Any files created in /home/ admin,

group automatically set as adminuser.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: mkdir /home/admins

chgrp ‐R adminuser /home/admins

chmodg+w /home/admins

chmodg+s /home/admins



QUESTION 31

SIMULATION



Install the Kernel Upgrade.

Install suitable kernel update from:

http://server.domain11.example.com/pub/updates.

Following requirements must be met:

Updated kernel used as the default kernel of system start‐up.

The original kernel is still valid and can be guided when system starts up.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: Using the browser open the URL in the question, download kernel file to root or home directory.

uname –r// check the current kernel version

rpm –ivh kernel‐*.rpm

vi /boot/grub.conf// check

Some questions are: Install and upgrade the kernel as required. To ensure that grub2 is the default item for

startup.

Yum repo : http://content.example.com/rhel7.0/x86‐64/errata

OR

uname ‐r  // check kernel

Yum‐config‐manager ‐‐add‐repo=“http://content.example.com/rhel7.0/x86‐64/ errata”

Yum clean all

Yum list kernel// install directly

Yum ‐y install kernel// stuck with it, do not pipe! Please do not pipe!

Default enable new kernel grub2‐editenv list// check

Modify grub2‐set‐default “kernel full name”

Grub2‐mkconfig –o/boot/grub2/grub.cfg// Refresh

QUESTION 32

SIMULATION



Binding to an external validation server.

System server.domain11.example.com provides a LDAP validation service, your system should bind to this

service as required:

Base DN of validation service is dc=example,dc=com

LDAP is used for providing account information and validation information Connecting and using the

certification of http://server.domain11.example.com/pub/EXAMPLE‐CA‐CERT to encrypt

After the correct configuration, ldapuser1 can log into your system, it does not have HOME directory until you

finish autofs questions, ldapuser1 password is password.

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: yum ‐y install sssd authconfig‐gtk krb5‐workstation authconfig‐gtk // open the graphical interface

Modify user account database to ldap, fill up DN and LDAP SERVER as questions required, use TLS to

encrypt connections making tick, write http://server.domain11.example.com/pub/EXAMPLE‐CA‐CERT to

download ca, authentication method choose ldap password.

You can test if the ldapuser is added by the following command:

Id ldapuser1

Note: user password doesn’t not need to set



QUESTION 33


SIMULATION

Configure NTP.

Configure NTP service, Synchronize the server time, NTP server: classroom.example.com

Answer: See explanation below.

Explanation

Explanation/Reference:

Explanation: Configure the client:

Yum ‐y install chrony

Vim /etc/chrony.conf

Add: server classroom.example.com iburst

Start: systemctl enable chronyd

systemctl restart chronyd

Validate: timedatectl status



QUESTION 34

SIMULATION

Configure autofs.

Configure the autofs automatically mount to the home directory of LDAP, as required:

server.domain11.example.com use NFS to share the home to your system. This file system contains a pre

configured home directory of user ldapuserX.

Home directory of ldapuserX is:

server.domain11.example.com /home/guests/ldapuser

 

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