IT Questions and Answers :)

Wednesday, February 28, 2018

Which VMware vSphere feature, when configured, streams a guest VM's changes to an exact replica VM on another host to prevent outages and data loss?

Which VMware vSphere feature, when configured, streams a guest VM's changes to an exact replica VM on another host to prevent outages and data loss?


  • DRS
  • High Availability
  • Fault Tolerance
  • Distributed Virtual Switching



EXPLANATION

VMware's Fault Tolerance (FT) feature allows you to protect a VM with an exact copy on another host machine. All of the changes are synced to the copy, so if the host fails in any way, vSphere will activate this copy. The effect is instantaneous, and allows you to provide constant uptime for mission-critical VMs.
You can read about Fault Tolerance, as well as its requirements and restrictions here: https://www.vmware.com/products/vsphere/features/fault-tolerance
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Motherboards that support more than four sticks of RAM may require what to function properly?

Motherboards that support more than four sticks of RAM may require what to function properly?

  • Buffered RAM
  • Dual-channel RAM
  • ECC RAM
  • DDR3 RAM 

 
Motherboards that support more than four sticks of RAM may require what to function properly?

EXPLANATION

Motherboards that support more than four sticks of RAM may require buffered RAM to function properly.This helps you get around the electrical hassles, by adding a buffering chip to the DRAM stick that acts as an intermediary between the DRAM and the MCC.

SOURCE

https://www.coursehero.com/file/p7tjkcd/a-The-motherboard-requires-SDRAM-not-RDRAM-b-The-motherboard-requires-DDR-SDRAM/
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Tuesday, February 27, 2018

All email services are based on which software model?

All email services are based on which software model?

  • SMTP
  • Client/server
  • POP3
  • TCP 

 
All email services are based on which software model?

EXPLANATION

The client–server model of computing is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. A server host runs one or more server programs which share their resources with clients. A client does not share any of its resources, but requests a server's content or service function. Clients therefore initiate communication sessions with servers which await incoming requests.
Examples of computer applications that use the client–server model are email, network printing, and the web.

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Monday, February 26, 2018

What happens when a volatile variable is declared in Java programming?

What happens when a volatile variable is declared in Java programming?

  • All reads and writes go straight to main memory
  • It holds a lock
  • It behaves as if enclosed in an asynchronous block
  • The value of the variable will be cached locally 

 
What happens when a volatile variable is declared in Java programming?

EXPLANATION

The Java volatile variable is an example of a special mechanism to guarantee that communication happens between threads. Basically, the value of the variable can be modified by different threads. When you declare a volatile variable, the value of this variable will never be cached thread-locally. Instead, all reads and writes will go straight to main memory. Access to the variable acts as though it is enclosed in a synchronized block, synchronized on itself.
Access to a volatile variable never has the potential to block because you can only ever do a simple read or write, so unlike a synchronized block it never holds on to any lock. Because of this, volatile variables are not suited for cases where you want to use read-update-write as an atomic operation, unless you are willing to miss an update. 

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Friday, February 23, 2018

CRUD is create, read, update and delete. How can we interpret in sql commands?

CRUD is create, read, update and delete. How can we interpret in sql commands?

  • Create, Read, Upgrade and Delete;
  • Create, Read, Update and Delete;
  • Insert, Select, Upgrade and Delet;
  • Insert, Select, Update and Delete; 

 
CRUD is create, read, update and delete. How can we interpret in sql commands?

EXPLANATION

This procedure performed using SQL is known as CRUD - Create, Read, Update and Delete which is nothing more than the composition of the basic operations that an application performs in a database, creating, reading, updating and deleting data. See the abbreviation CRUD mapped below:

Create -> INSERT;

Read -> SELECT;

Update -> UPDATE;

Delete -> DELETE.

SOURCE

https://www.sqlshack.com/creating-using-crud-stored-procedures/

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What is the term for a rogue access point that serves as a man in the middle from which further attacks can be carried out?

What is the term for a rogue access point that serves as a man in the middle from which further attacks can be carried out?

  • War driving
  • Twin driving
  • War twinning
  • Evil twin 
What is the term for a rogue access point that serves as a man in the middle from which further attacks can be carried out?

EXPLANATION

An evil twin is a rogue access point used for malicious purposes. The attacker acts as a man in the middle.
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Thursday, February 22, 2018

In the early days of computer technology, what type of memory had to be hand made rather than by machine?

In the early days of computer technology, what type of memory had to be hand made rather than by machine?

  • Thin film memory
  • EPROM
  • Magnetic core memory
  • Bubble Memory 

 
In the early days of computer technology, what type of memory had to be hand made rather than by machine?

EXPLANATION

Magnetic core memory was almost always "woven" by hand in spite of repeated attempts to automate the process. Core uses tiny magnetic beads (the cores), through which wires are threaded to write and read information.

SOURCE

https://en.wikipedia.org/wiki/Magnetic-core_memory
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Wednesday, February 21, 2018

Which is the standard file extension used by VMWare for virtual hard drive images?

Which is the standard file extension used by VMWare for virtual hard drive images?

  • VHD (Virtual Hard Disk)
  • VDI (Virtual Disk Image)
  • VMDK (Virtual Machine Disk)
  • HDD (Hard Disk Drive) 

 
Which is the standard file extension used by VMWare for virtual hard drive images?

EXPLANATION

VMDK is the standard used by VMWare and is supported by several other virtual hypervisors.  It can contain the entire virtual machine, including settings.
VHD is the standard typically used by Microsoft Hyper-V.  It represents a single virtual drive, and does not contain configuration settings for the rest of the virtual machine.
HDD is the standard for Parallels.
VDI is the standard and default for type-2 hypervisor VirtualBox; it can use and create all four of the listed formats, however.

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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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