IT Questions and Answers :)

Tuesday, February 20, 2018

What is the minimum size of the IPv6 packet header?

What is the minimum size of the IPv6 packet header?

  • 36 octets
  • 32 octets
  • 40 octets
  • 48 octets 

 
What is the minimum size of the IPv6 packet header?

EXPLANATION

The IPv6 packet header has a minimum size of 40 octets. Options are implemented as extensions. This provides the opportunity to extend the protocol in the future without affecting the core packet structure.
RFC 2460; Internet Protocol, Version 6 (IPv6) Specification, S. Deering, R. Hinden (December 1998)
https://en.wikipedia.org/wiki/IPv6
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Monday, February 19, 2018

In MacOS, what terminal command will temporarily reduce the frequency of the "spinning beach ball" icon caused by a RAM shortage?

In MacOS, what terminal command will temporarily reduce the frequency of the "spinning beach ball" icon caused by a RAM shortage?

  • purge ram
  • purge mem
  • sudo purge
  • sudo clearmem 

 
In MacOS, what terminal command will temporarily reduce the frequency of the "spinning beach ball" icon caused by a RAM shortage?

EXPLANATION

Purging the memory clears on inactive memory allocation, thus making it usable to applications. Sudo purge accomplishes this.

SOURCE

http://osxdaily.com/2012/04/24/free-up-inactive-memory-in-mac-os-x-with-purge-command/
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Friday, February 16, 2018

Which of the following is NOT a PowerShell comparison operator type?

Which of the following is NOT a PowerShell comparison operator type?

  • Matching
  • Containment
  • Replacement
  • Assignment
 
 
Which of the following is NOT a PowerShell comparison operator type?

EXPLANATION

Comparison operators are used in PowerShell to compare values. There are four types of operators: equality, matching, containment, and replacement. The one big gotcha in PowerShell has to do with syntax: rather than using traditional comparison operators like < or > PowerShell uses -lt or -gt to perform comparisons.

SOURCE

https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_comparison_operators?view=powershell-5.1
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Thursday, February 15, 2018

Two organizations are partnering and sharing systems. Which of the following would outline how the shared systems interface?

Two organizations are partnering and sharing systems. Which of the following would outline how the shared systems interface?

  • BPA
  • SLA
  • ISA
  • ROA 

 
Two organizations are partnering and sharing systems. Which of the following would outline how the shared systems interface?

EXPLANATION

An interconnection security agreement (ISA) documents the technical requirements of a connection between organizations, such as the basic components, methods and levels of interconnectivity, and potential security risks.
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Wednesday, February 14, 2018

You need to encrypt and compress your backups before replicating them off site. Which is best practice, compress then encrypt, or encrypt then compress?

You need to encrypt and compress your backups before replicating them off site. Which is best practice, compress then encrypt, or encrypt then compress?

  • Neither!
  • Encrypt first!
  • Doesn't matter!
  • Compress first! 
 
You need to encrypt and compress your backups before replicating them off site. Which is best practice, compress then encrypt, or encrypt then compress?

EXPLANATION

If you encrypt the data first, it will be randomized and unintelligible by your compression application which need to compress the data in a logical format.  
Compressing then encrypting is the way to go.

SOURCE

https://stackoverflow.com/questions/4676095/when-compressing-and-encrypting-should-i-compress-first-or-encrypt-first 
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Tuesday, February 13, 2018

For every unique constraint on a column, SQL server will create which of the following?

For every unique constraint on a column, SQL server will create which of the following?

  • An entry for that column
  • A non-clustered index for that column
  • A clustered index for that column
  • A filtered index 

 
For every unique constraint on a column, SQL server will create which of the following?

EXPLANATION

For every unique constraint on a column, SQL server creates a non-clustered index. A non-clustered index has a structure separate from the data rows. It contains non-clustered index key values and each key value entry has a pointer to the data row that contains the key value.

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Unix time is the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on what date?

Unix time is the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on what date?

  • Saturday, January 1, 2000
  • Sunday, December 28, 1969
  • Thursday, January 1, 1970
  • Monday, January 1, 1900 

 
Unix time is the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on what date?

EXPLANATION

Unix time counts the number of seconds that have elapsed since 00:00:00 UTC on January 1, 1970. It is used in Unix-like operating systems and file formats. Because it doesn't deal with leap seconds, it is not a true representation of UTC. Check out Unix time for yourself by typing "date +%s" on the command line.

Fun fact: December 28, 1969, is Linus Torvalds' birthday, which makes him older than Unix.

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Saturday, February 10, 2018

Thursday, February 8, 2018

What Azure BGP Private ASN are reserved?

What Azure BGP Private ASN are reserved?

  • 65515, 65517, 65518, 65519, 65520
  • 54000, 54100, 54200, 54300, 54400
  • 60001, 60002, 60003, 60004, 60005
  • 67715, 67717, 67718, 67719, 67720 

 
What Azure BGP Private ASN are reserved?

EXPLANATION

Private and Public Azure ASN's can be foudn here:
https://docs.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-bgp-overview

SOURCE

https://docs.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-bgp-overview
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Wednesday, February 7, 2018

Which of the following standards relates to a video compression standard?

Which of the following standards relates to a video compression standard?

  • G.711
  • G.729
  • H.264
  • H.323 

Which of the following standards relates to a video compression standard?

H.264 is an industry standard for video compression, the process of converting digital video into a format that takes up less capacity when it is stored or transmitted. Video compression (or video coding) is an essential technology for applications such as digital television, DVD-Video, mobile TV, video conferencing and internet video streaming.

SOURCE

https://www.vcodex.com/h264-resources/
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Tuesday, February 6, 2018

In VMware ESXi, when expanding a virtual disk, which of the follwing should not exist?

In VMware ESXi, when expanding a virtual disk, which of the follwing should not exist?

  • A new virtual machine
  • Backup
  • Snapshots
  • Available space 

 
In VMware ESXi, when expanding a virtual disk, which of the follwing should not exist?

EXPLANATION


The Prerequisites for expanding a virtual disk are:

■ Power off the virtual machine.
■ Verify that the virtual disk is not mapped or mounted. You cannot expand a virtual disk while it is mapped or mounted.
■ Verify that the virtual machine has no snapshots.
■ Verify that the virtual machine is not a linked clone or the parent of a linked clone.

SOURCE

https://pubs.vmware.com/workstation-9/index.jsp?topic=%2Fcom.vmware.ws.using.doc%2FGUID-73BEB4E6-A1B9-41F4-BA37-364C4B067AA8.html
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Monday, February 5, 2018

What does the x stand for in AGP 8x?

What does the x stand for in AGP 8x?

  • Times Graphic Speed
  • Times FSB Speed
  • Times CPU Speed
  • Times original AGP Speed 
 
 
What does the x stand for in AGP 8x?

EXPLANATION

AGP (Accelerated Graphics Port) is a high-speed 32-bit port from Intel for attaching a display adapter to a PC. It provides a direct connection between the card and memory, and only one AGP slot is on the motherboard. AGP was introduced as a higher-speed alternative to PCI display adapters, and it freed a PCI slot for another peripheral device. The brown AGP slot is slightly shorter than the white PCI slot and is located about an inch farther back. AGP is superseded by PCI Express.
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Friday, February 2, 2018

What range of values does Hexadecimal use?

What range of values does Hexadecimal use?

  • 0-9 and A-F
  • 1-17
  • 0-16
  • 1-10 and A-E 

 
What range of values does Hexadecimal use?

EXPLANATION

In mathematics and computing, hexadecimal (also base 16, or hex) is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F(or alternatively a, b, c, d, e, f) to represent values ten to fifteen.

SOURCE

https://en.wikipedia.org/wiki/Hexadecimal
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Thursday, February 1, 2018

Macro, Micro, Pico, Femto and Umbrella are all types of what?

Macro, Micro, Pico, Femto and Umbrella are all types of what?

  • Cell sizes in a GSM network
  • GSM filters
  • GSM interfaces
  • Uplink and downlink channels 

Macro, Micro, Pico, Femto and Umbrella are all types of what?

EXPLANATION

GSM mobile phone networks are "cellular," which means that mobile phones connect to it by nearest cell.
MACRO cells can be regarded as cells where the base station antenna is installed on a mast or larger building structures that are taller than an average roof-top level. Cell radius is typically from 1 up to 35 km.
MICRO cells are cells whose antenna height below average rooftop level and are typically used in urban areas. Size is from 400 m to 2 km. 
PICO cells are small cells whose diameter is only few dozen meters; they are used mainly in indoor applications.
UMBRELLA cells: A layer with micro cells is covered by at least one macro cell, and a micro cell can in turn cover several pico cells. A covering cell is called an umbrella cell.

SOURCE

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