IT Questions and Answers :)

Friday, May 17, 2019

When it comes to virtual memory, which of the following is true of "thrashing"?

When it comes to virtual memory, which of the following is true of "thrashing"?

  • It can be caused by poor paging algorithms
  • It is a natural consequence of virtual memory systems
  • It always occurs on large computers
  • It can always be avoided by swapping 

EXPLANATION

 With virtual memory, which is illustrated in the accompanying figure, when an operating system spends much of its time paging, instead of executing application software, it is said to be thrashing.

 true

In operating systems that implement a virtual memory space the programs allocate memory from an address space that may be much larger than the actual amount of RAM the system possesses. The OS is responsible for deciding which programs "memory" is in actual RAM. It needs a place to keep things while they are "out". This is what is called "swap space", as the OS is swapping things in and out as needed. When this swapping activity is occurring such that it is the major consumer of the CPU time, then you are effectively thrashing. You prevent it by running fewer programs, writing programs that use memory more efficiently, adding RAM to the system, or maybe even by increasing the swap size. 

A page fault occurs when the memory access requested (from the virtual address space) does not map to something that is in RAM. A page must then be sent from RAM to swap, so that the requested new page can be brought from swap to RAM. As you might imagine, 2 disk I/Os for a RAM read tends to be pretty poor performance. 

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What is the network name needed to connect to a wireless access point?

What is the network name needed to connect to a wireless access point?

  • Basic Service Address (BSA)
  • MAC address
  • Service Set Identifier (SSID)
  • Extended Service Set (ESS) 

EXPLANATION

SSID is short for service set identifier. In layman's terms, an SSID is the name for a Wi-Fi network.
People typically encounter an SSID most often when they are using a mobile device to connect to a wireless network. For example, if you take your laptop to the coffee shop and attempt to connect to the local Wi-Fi network, your screen will display a list of SSIDs — this is the names of all the networks that are within range of your mobile device. You'll select the name of the local network you want to connect to and then enter the password (if necessary) to connect.
Note that some public networks, typically managed by a business, may require you to first read and agree to an online terms of service (ToS) before allowing you to connect.

SOURCE

https://en.wikipedia.org/wiki/Kibibyte

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Which nested RAID level combines block-level striping with distributed parity?

Which nested RAID level combines block-level striping with distributed parity?

  • RAID 30
  • RAID 60
  • RAID 50
  • RAID 10 
Which nested RAID level combines block-level striping with distributed parity?

EXPLANATION

RAID 50 (RAID 5+0)

A RAID 50 combines the straight block-level striping of RAID 0 with the distributed parity of RAID 5. This is a RAID 0 array striped across RAID 5 elements. It requires at least 6 drives.

Provides great balance between storage performance, storage capacity, and data integrity that’s not necessarily found in other RAID levels.One drive from each of the RAID 5 sets could fail without loss of data.

The time spent in recovery (detecting and responding to a drive failure, and the rebuild process to the newly inserted drive) represents a period of vulnerability to the RAID set.

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Which of these is NOT a Linux desktop?

Which of these is NOT a Linux desktop?

  • Butterfly
  • Gnome
  • Cinnamon
  • XFCE 
Which of these is NOT a Linux desktop?

EXPLANATION

 Butterfly is a xterm compatible terminal that runs in your browser.

Features

  • xterm compatible (support a lot of unused features!)
  • Native browser scroll and search
  • Theming in css / sass (20 preset themes) endless possibilities!
  • HTML in your terminal! cat images and use <table>
  • Multiple sessions support (à la screen -x) to simultaneously access a terminal from several places on the planet!
  • Secure authentication with X509 certificates!
  • 16,777,216 colors support!
  • Keyboard text selection!
  • Desktop notifications on terminal output!
  • Geolocation from browser!
  • May work on firefox too!
https://github.com/paradoxxxzero/butterfly
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Which of the following would log you into Azure Resource Manager via Powershell

Which of the following would log you into Azure Resource Manager via Powershell

  • login-azureaccount
  • login-azurermaccount
  • new-azuresession
  • login-azure 

 
Which of the following would log you into Azure Resource Manager via Powershell

EXPLANATION

Login-AzureRMAccount requires you have the AzureRM modules installed. and will prompt you for credentials. You can also extend this to login to a particular Subscription under that login.
For example: login-azurermaccount -subscriptionid "Dev Sub"

SOURCE

https://4sysops.com/archives/auto-login-to-azure-with-powershell/
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