Linux

Describe hard

Hard linked files are direct copies of one another, as they share the same inode and inode number. deleting a hard linked file does not delete all the other hard linked files.

True or False: A route table is a list of TCP/IP networks that is stored in system memory.

True

True or False: After a process has been started, you can change its priority by using the renice command.

True

True or False: All DNS servers contain a DNS cache file.

True

True or False: Performance problems are caused by hardware, not software.

True

True or False: The ARCfour encryption algorithm uses variable-length keys up to 2048 bits in length.​

True

True or False: The Very Secure FTP daemon is a stand-alone daemon.

True

True or False: The compress utility preserves the original ownership, modification, and access time for each file that it compresses.

True

True or False: The cpio command has the ability to handle long filenames and can be used to back up device files.​

True

True or False: logs from the cron daemon (crond) can be viewed using the command journalctl _COMM=crond

True

Explain the difference between an absolute and a relative pathname, and why one might be used over the other.

absolute is the full pathname of a certain file/directory starting from the root directory. relative is the pathname of a target file or directory relative to your current directory in the tree, can save on typing and error reduction

True or False: By default, the smb.conf file shares all printers and home directories for recognized Windows users.

true

Describe character devices and block devices, and explain the difference between them. Provide examples of each type of device

Character: character-by-character to and from the device. ex. tape drive Block Devices: transfers chunks or blocks of information at a time by using physical memory to buffer the transfer. ex. floppy disks, CD-ROMs, DVDs, USB flash drives, and hard disks,

True or False: If some users, such as software developers, need to run certain commands as the root user in certain situations, it is best to allow them to log on to the root user account via the su command.

False

True or False: The command strings /bin/echo displays the raw binary characters inside the /bin/echo binary executable program.

False

True or False: The killall command uses the PID to kill a process.

False

True or False: Performing regular system backups and identifying potential problem areas are examples of reactive maintenance.

False

True or False: Pressing the Esc key at the prompt while using the more command displays a help screen.

False

True or False: When connecting to the vsftpd daemon using an FTP client utility as the user "anonymous", you will be placed in the root user's home directory.

False

How do you configure a NIC?

Fedora Linux automatically configures the appropriate driver to allow the Linux kernel to work with the NIC driver. NIC drivers are contained in modules ending in .ko that can be inserted into the Linux kernel. They can be manually loaded in using the insmod or modprobe command.

What are the two golden rules that should guide you during any troubleshooting process? Describe each rule

Prioritize problems from urgent to least. Try to solve the root of the problem. Rather then try to find a quick fix to get it working temporarily, investigate the issue and find the cause of the issue and find a way to improve that part to reduce failures again.

Describe the telnet and SSH utilities. What is the difference between them?

Telnet transfers data from the remote computer and the host computer using clear text. not secure. SSH encrypts all the data that is transferred between the devices making it secure.

True or False: When you print to a printer class, the print job is send to the first available printer in the printer class.

True

True or False: You can use wildcard metacharacters with the find command.

True

True or False: A route table is a list of TCP/IP networks that is stored in system memory.

True

True or False: When you insert a DVD while in a GUI environment, it is automatically mounted by the system to a directory underneath the /media directory that is named for the label on the DVD.

True

True or False: You can choose to use a window manager only, and not use a desktop manager.

True

True or False: Zombie processes are also known as defunct processes.​

True

Describe how virtual memory is used

When programs are executed that require a lot of resources on the computer, information is continuously swapped from the physical memory to the virtual memory on the hard disk, and vice versa.

Describe the DNS lookup process.

When you go to a Web server on the Internet, the Web browser performs a forward lookup of the FQDN such that it can contact the IP address of the Web server. This forward lookup can be performed by a DNS server or a series of DNS servers.

When backing up a system, what type of files should be archived?

back up user files from home directories and any important system configuration files such as /etc/passwd. In addition to this, you might want to back up files used by system services. For example, you need to back up Web site files if the Linux computer is used as a Web server.

Provide information on decision constructs, and explain how to use the most common type of decision construct.

decision constructs. Like the if. else if statements. if this then do that. the computer follows a set of rules in which it comes to its end point. if is the most common.

What do you do if the NIC is not detected during installation?

need to search for and install the appropriate driver module on your system.

What methods can be used to physically secure local computers?

Computers typically have a point in which a lock or wire can be attached. This will prevent people from getting into them as well as taking them as the wire can be attached to the desk.

True or False: Any command that can be executed on the command line can also be placed inside any environment file.

True

True or False: Each computer on a network requires a unique way to identify itself and to refer to other computers. One way this is accomplished is by using IP addresses.

True

True or False: If the /etc/at.allow and /etc/at.deny files do not exist, only the root user is allowed to schedule tasks using the at daemon.

True

True or False: The email command is an example of a Mail User Agent (MUA).​

True

True or False: Because the Makefile often includes some documented items, it is good form to read the Makefile after running the configure script

True

True or False: Linux uses a logical directory tree to organize files into different folders.

True

True or False: The compress utility preserves the original ownership, modification, and access time for each file that it compresses

True

True or False: The more filesystems that are used on a system, the less likely a corrupted filesystem will interfere with normal system operations.

True

What is VNC? How does it transfer graphics across the network?

Virtual Network Computing (VNC) is a graphical option for administrating a Linux system remotely. VNC uses Remote FrameBuffer (RFB) to transfer information.

Describe what a fully qualified domain name (FQDN) is, and how IP addresses are related to FQDNs.​ Give an example of how you would use a FQDN.

Server name. Includes all parts of the name. Only there for peoples convenience Computer uses the IP address to access the information you need while the FQDN is what people see an example being google.ca rather than 8.8.8.8 as we are better with names than nubers

Describe what a fully qualified domain name (FQDN) is, and how IP addresses are related to FQDNs.​ Give an example of how you would use a FQDN.

Servers on the Internet are identified by names, which are known as fully qualified domain names (FQDNs). When using a web browser such as Internet Explorer or Netscape to request information from a Web server,​ the FQDN is typically used. These FQDNs exist only for the convenience of the human beings who use computer networks. Computers themselves rely on IP addresses. A browser gets the IP address associated with a FQDN by contacting a Domain Name System (DNS) server, which maintains a list of the proper FQDN to IP mappings.

True or false? The /etc/rc.d/rc 5 script only executes files that start with S in the /etc/rc.d/rc5.d/ directory.

False

Describe the difference between full and incremental backups. Explain how both might be used to implement a back-up strategy

Full: Full snapshot of entire system - takes alot of time - weekends Incremental: only files that have changed - less time - weekdays

What is NFS? How do you access files using a configured NFS Server?

Network File System (NFS) It's used on UNIX, Linux and Mac OS systems. It allows them to share files. In NFS one computer shares a directory and the rest can connect into that share by mounting it via the /mnt command using the hosts IP address.

What is NIS? What is a master and slave NIS server?

Network Information Service (NIS) coordinate common configuration files across several Linux computers within an organization. can configure an NIS master server to send all NIS map configurations to NIS slave servers. master NIS server can send NIS map configuration directly to NIS clients.

What are the two golden rules that should guide you during any troubleshooting process? Describe each rule.

Prioritize problems—If you need to solve multiple, prioritize the problems according to severity and spend the most time on the most severe problem. Becoming fixated on a small problem and ignoring larger issues results in much lower productivity. If a problem is too difficult to solve in a given period of time, it is good practice to ask for help. Try to solve the root of the problem—Some solutions might appear successful in the short term, yet fail over the long term because of an underlying problem. Effective troubleshooting requires good instincts, which in turn come from a solid knowledge of the system hardware and configuration. To avoid missing the underlying cause of any problem, try to justify why a certain solution was successful. If it is unclear why a certain solution was successful, it is likely that you have missed an underlying cause of the problem that might need to be remedied in the future to prevent the same problem from recurring.

Give examples of configuration files that NIS is commonly used to coordinate

most common use is password databases. allows user and password across multiple systems

Describe virtual memory,

physical memory (RAM) is being used excessively, can be used to store information that would normally reside in the physical memory.

When backing up a system, what types should not?

you don't have to include temporary files in the /tmp and /var/tmp directories, nor do you need to include any cached Internet content found under each user's home directory.

Explain why scheduling commands can be beneficial, and detail some of the methods available for scheduling commands.

Scheduling commands can be good as they can allow for specialized software or anything else like backups to auto start or automatically run at a specified time and or shut down after x amount of time. There are two different daemons to schedule commands: The at daemon (atd) can be used to schedule a command to execute once in the future. The cron daemon (crond). It's used to schedule a command to execute repeatedly in the future.

How does DHCP automatically configure IP addresses?

The computer sends a DHCP broadcast on the network requesting a IP configuration. DHCP server then sees the broadcast and replies with information. DHCP server will keep track of all the IP's it's given out so that it doesn't give out the same one more than once.

Explain what a metacharacter is, and detail the significance of the $ metacharacter.

A metacharacter is a keyboard characters that has a special meaning. $ character tells the shell that the following text refers to a variable. A variable is simply a piece of information that is stored in memory

Describe shell variables, and explain environment and user-defined variables.

A variable is a reserved portion of memory containing information that might be accessed. environment variables: set by the system and contain information that the system and programs access regularly. user-defined variables: created by the user

How can netfilter/iptables be used to create a firewall service?

Correct Netfilter discards certain network packets according to chains of rules that are stored in your computer's memory. By default, you can specify firewall rules for three types of chains: ​ INPUT chain, for network packets destined for your computer ​ FORWARD chain, for network packets that must pass through your computer (if you are a router) ​ OUTPUT chain, for network packets that originate from your computer ​ In most cases, no rules exist for the INPUT, FORWARD, or OUTPUT chains after a Linux installation. To create rules that are used for each chain, you must use the iptables command. Rules can be based on the source IP address, destination IP address, protocol used (TCP, UDP, ICMP), or packet status.

Describe what a subnet mask is, and explain why it is used.

Each computer with an IPv4 address must also have a subnet mask to define which part of its IP address is the network ID and which part is the host ID.

True or False: It is acceptable to use shell metacharacters when naming files.

False

True or False: The secure log file contains information regarding the last user to log in to a system.​

False

True or False: Volumes can contain a filesystem but they can't be mounted to directories within the Linux filesystem hierarchy.​

False

True or False: You are limited to using one pipe | metacharacter on the command line to pipe information from one command to another command.

False

True or False: A swap partition contains a filesystem.

False

True or False: Almost all hardware problems are the result of damaged hardware.

False

True or False: On closed-source operating systems, hot fixes for software bugs are deployed very quickly.​

False

True or False: When using the gzip utility, the -1 option is also known as best compression and results in a higher compression ratio

False

Detail shell scripts and explain how they are used and executed.

Shell has the ability to execute text files containing commands and special constructs. shell scripts are typically used to create custom programs that perform administrative tasks on Linux systems. Any command that can be entered on the command line in Linux can be entered into a shell script.

detail how a subnet mask it is used to determine the network ID of an IP address.

Subnet masks are composed of four octets. The simplest subnet masks use only the values 0 and 255. An octet in a subnet mask of 255 is part of the network ID. An octet in a subnet mask of 0 is part of the host ID.

What are the three main structural sections of a Linux filesystem? Describe each section.

Superblock, Inode table, and data blocks. superblock: information about the filesystem in general inode table consists of several inodes blocks are known as allocation units because they are the unit by which disk space is allocated for storage.

What is symbolic link

Symbolic links do not share the same inode and inode number with their target file; one is merely a pointer to the other so both files have different sizes.

Explain the difference between an absolute and a relative pathname, and why one might be used over the other.

The absolute pathname to a file or directory is the full pathname of a certain file or directory starting from the root directory. A relative pathname is the pathname of a target file or directory relative to your current directory in the tree. Although absolute pathnames are straightforward to use as arguments to commands when specifying the location of a certain file or directory, relative pathnames can save you a great deal of typing and reduce the potential for error if your current directory is far away from the root directory.

Describe the telnet and SSH utilities. What is the difference between them?

The easiest way to perform administration on a remote Linux computer is via a command-line interface. The telnet command has traditionally been used to obtain a command-line shell on remote UNIX and Linux servers across the network that run a telnet server daemon. Nearly all operating systems today, such as Windows, Macintosh, and UNIX, come with a telnet command. ​ Once the telnet daemon has been configured, you can connect to it from a remote computer. Simply specify the host name or IP address of the target computer to the telnet command and log in as the appropriate user and password. A shell obtained during a telnet session runs on a pseudoterminal (a terminal that does not obtain input directly from the computer keyboard) rather than a local terminal and works much the same way a normal shell does. You can execute commands and use the exit command to kill the BASH shell and end the session. ​ Although the telnet, rlogin, rcp, and rsh commands can be quickly used to perform remote administration, they do not encrypt the information that passes between computers. Secure Shell (SSH) was designed as a secure replacement for these commands that encrypts information that passes across the network. To connect to a remote Linux computer running sshd, you can use the ssh command followed by the host name or IP address of the target computer. Your local user name will be passed to the server automatically during the SSH request, and you will be prompted to supply the password for the same user on the target computer.

Describe how the /etc/passwd and /etc/shadow files are used in the authentication process. Why are two files used instead of one? How can you convert a system to use the /etc/shadow file to store passwords?

The system database that contains user account information consists of two files: /etc/passwd and /etc/shadow. Every user has a line that describes the user account in /etc/passwd and a line that contains the encrypted password and expiration in /etc/shadow. ​ Older versions of Linux stored the encrypted password in the /etc/passwd file and did not use an /etc/shadow file at all. which was not as secure as today's system.

how the dump/restore utility can assist in this implementation. Provide an example.

dump/restore utility can be used to back up only certain files and directories, it was designed to back up entire filesystems to an archive and keep track of these filesystems in a file called /etc/dumpdates.

Define hard disk quotas, and then explain how they are used. Then, describe the differences between soft limits and hard limits

restrictions to the amount of space available to the users they can be applied to users or groups of users. Soft limits are hard disk quotas that the user can exceed for a certain period of time hard limits are rigid quotas that the user cannot exceed.

What types of media are commonly used for archives? What type of media is most commonly used for archiving on Linux systems?

tapes, CDs, DVDs, or hard disks. Traditionally, tapes were used to back up data. Today, large backups are typically performed using separate hard disks. Smaller backups are performed using CDs or DVDs, which require special burning software described later in this chapter.

What is the disadvantage of using the cat command to display a very large text file? How can you get around this problem?

text files can be too large to be displayed. To get around: display text files in a page-by-page fashion by using either the more or less commands.

The difference between developmental kernels and production kernels, and explain how the minor number is used to distinguish between the two.

​Developmental kernels are not fully stable. Production kernels are developmental kernels are very stable and have been thoroughly tested. odd = developmental kernel even= production kernel.