What is the default port used by Postfix?

What is the default port used by Postfix?

• 25
• 45
• 37
• 20 

 

EXPLANATION

Postfix is an open source mail transfer agent (MTA) that is used to route and deliver emails. Postfix is the alternate of widely
used Sendmail MTA. Postfix uses port number 25 (SMTP) by default.

Read More

What type of RAID is RAID 2?

What type of RAID is RAID 2?

• Byte-level striping with dedicated parity.
• A striped set from a series of mirrored drives.
• Block-level striping with dedicated parity.
• Bit-level striping with dedicated Hamming-code parity. 

EXPLANATION

RAID 2
RAID 2 consists of bit-level striping with dedicated Hamming-code parity. All disk spindle rotation is synchronized and data is striped such that each sequential bit is on a different drive. Hamming-code parity is calculated across corresponding bits and stored on at least one parity drive. This level is of historical significance only; although it was used on some early machines (for example, the Thinking Machines CM-2), as of 2014 it is not used by any commercially available system.
RAID 2

SOURCE

https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_2 

Read More

In Linux system, which command will print the output of log file in reverse ?

In Linux system, which command will print the output of log file in reverse ?

• less
• cat
• tac
• rcs 

 

EXPLANATION

Let's assume that we have a log file named "Letters" that contains: A B C D (in separate lines).
To view the content of the log file in Linux terminal, the command will be:

linux@machine:~$ sudo cat Letters

And we will get the output:
A
B
C
D

To view the content of the log file in reverse, the command will be:

linux@machine:~$ sudo tac Letters

And we will get the output:
D
C
B
A

SOURCE

https://www.tecmint.com/learn-linux-cat-command-and-tac-command/

Read More

While working on an issue on a clients network you learn that you will be using the 1000BaseCX standard. What type of cable will you be using.

While working on an issue on a clients network you learn that you will be using the 1000BaseCX standard. What type of cable will you be using.

• CoreXtended Fiber
• Single-mode fiber
• Multimode fiber
• STP

EXPLANATION

The 1000BaseCX standard specifies Gigabit Ethernet over STP cabling.

1. Multi-mode Fiber is incorrect because 1000BaseSX and 1000BaseLX specify Gigabit Ethernet over two types of Multi-mode fiber.
2. Single-mode fiber is used with 100BaseFX standard.
3. As far as CoreXtended Fiber, there anin't no such animal.
   

SOURCE

http://www.thenetworkencyclopedia.com/entry/1000basecx/

Read More

Which of the following retains the information it's storing when the system power is turned off?

Which of the following retains the information it's storing when the system power is turned off?

• ROM
• RAM
• GPU
• CPU 

 

EXPLANATION

Read only memory (ROM) is nonvolatile, meaning that turning off the computer doesn't erase it. 

Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM can only be modified slowly, with difficulty, or not at all, so it is mainly used to store firmware (software that is closely tied to specific hardware, and unlikely to need frequent updates) or application software in plug-in cartridges.

Strictly, read-only memory refers to memory that is hard-wired, such as diode matrix and the later mask ROM (MROM), which cannot be changed after manufacture. Although discrete circuits can be altered in principle, integrated circuits (ICs) cannot, and are useless if the data is bad or requires an update. That such memory can never be changed is a disadvantage in many applications, as bugs and security issues cannot be fixed, and new features cannot be added.

More recently, ROM has come to include memory that is read-only in normal operation, but can still be reprogrammed in some way. Erasable programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM) can be erased and re-programmed, but usually this can only be done at relatively slow speeds, may require special equipment to achieve, and is typically only possible a certain number of times

Read More

In Windows Active Directory, what is the default time interval that the Knowledge Consistency Checker (KCC) uses for incremental syncs to review and update the Active Directory replication topology?

In Windows Active Directory, what is the default time interval that the Knowledge Consistency Checker (KCC) uses for incremental syncs to review and update the Active Directory replication topology?

• 48 hours
• 15 minutes
• 60 minutes
• 5 minutes 

 

EXPLANATION

By default, the knowledge consistency checker (KCC) reviews and makes modifications to the Active Directory replication topology every 15 minutes. The KCC ensures propagation of data, either directly or transitively, by creating and deleting connection objects as needed. The KCC recognizes changes that occur in the environment and ensures that domain controllers are not orphaned in the replication topology.

For more information on the KCC, see: https://technet.microsoft.com/en-us/library/cc961781.aspx

Read More

Which of the following types of attacks do hackers use to gain information from you without the use of a computer program?

Which of the following types of attacks do hackers use to gain information from you without the use of a computer program?

• Social Engineering
• Cross Site Scripting
• ARP Poisoning
• SQL Injection 

 

EXPLANATION

Social engineering, in the context of information security, refers to psychological manipulation of people into performing actions or divulging confidential information. A type of confidence trick for the purpose of information gathering, fraud, or system access, it differs from a traditional "con" in that it is often one of many steps in a more complex fraud scheme.
The term "social engineering" as an act of psychological manipulation of a human, is also associated with the social sciences, but its usage has caught-on among computer and information security professionals.

SOURCE

https://en.wikipedia.org/wiki/Social_engineering_(security)

Read More