RedHat RH302 Actual Questions

To understand the role of a boot loader, take a step back from Linux. When you boot your computer, the BIOS starts by detecting basic hardware, including your hard drives. Once it's done, it looks for the boot loader on the Master Boot Record of the first available disk. If you're working with an older PC, the BIOS can't find your boot loader unless it's located within the first 1,024 cylinders of the hard disk.

Newer BIOSes overcome this problem with Logical Block Addressing, which is also known as LBA mode. LBA mode reads 'logical' values for the cylinder, head, and sector, which allows the BIOS to 'see' a larger disk drive.

If you have multiple hard drives, there is one more caveat. If your drives are IDE hard drives, the /boot directory must be on a hard drive attached to the primary IDE controller. If your drives are all SCSI hard drives, the /boot directory must be located on a hard drive with SCSI ID 0 or ID 1. If you have a mix of hard drives, the /boot directory must be located on either the first IDE drive or a SCSI drive with ID 0. In other words, this is not an issue on the Red Hat exams unless the computer that you're tested on has more than two hard drives. And I believe that's less likely, as that would increase the cost of the exam.

If you are getting the Kernel panic error, it means it is boot loader related problem. Redhat Enterprise Linux uses the GRUB boot loader. You can pass the kernel parameter from the boot loader as well as you can correct the kernel parameter passing from boot loader from GRUB screen at boot time.

GRUB boot loader configuration file is: /etc/grub.conf

And Correct Configuration is:

default=0

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title Red Hat Enterprise Linux ES (2.6.9-5.EL)

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet

initrd /initrd-2.6.9-5.EL.img

Probably miss-configured the boot loader, so giving this problem. You can pass the correct parameter from GRUB prompt:

Table 3-3:GRUB Editing Commands

Command

Description

b

Boot the currently listed operating system

d

Delete the current line

e

Edit the current line

o

Create an empty line underneath the current line

O

Create an empty line above the current line

If you know all parameters and sequence of the boot loader you can enter in command prompt also.

Press c on GRUB screen.

Grub>root (hd0,0)

grub>kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet

grub>initrd /initrd-2.6.9-5.EL.img

grub>boot

Do the following steps as:

vi /etc/resolv.conf

nameserver 172.24.254.254

host server1.example.com

On every clients, DNS server is specified in /etc/resolv.conf. When you request by name it tries to resolve from DNS server.

Do the following steps as:

1.vi /etc/dhcpd.conf

ddns-update-style none;

option routers 192.168.0.1;

option domain-name “example.com”;

option domain-name-servers 192.168.0.254;

default-lease-time 21600;

max-lease-time 43200;

subnet 192.168.0.0 netmask 255.255.255.0

{

range 192.168.0.10 192.168.0.50;

}

/etc/dhcpd.conf file is used to configure the DHCP. Some global options i.e Gateway, domainname, DNS server specified using option keyword.

2. Check the SELinux Context, should be like this:

-rw-r--r-- root root system_u:object_r:dhcp_etc_t /etc/dhcpd.conf

3. If not use the restorecon –R /etc command to restore the selinux context of the file.

4. service dhcpd start | restart

Do the following steps as:

1.vi /etc/xinetd.d/telnet

service telnet {

only_from=192.168.0.0/24

access_times=09:00-17:00

}

2.chkconf telnet on

3.service xinetd restart

xinetd based services can manage by specifying host and time parameters. Only_from means connection allowed network, remaining hosts explicitly deny. access_times specify when service is available.