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 

 

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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In DNS terms what is the purpose of an "A" record?

In DNS terms what is the purpose of an "A" record?

• Resolves the MAC address of a host from its name
• Resolves the IP address of a host from its name
• Resolves the IP address of a host from the MAC address
• Resolves the Host name from its MAC address 

 

EXPLANATION

https://support.dnsimple.com/articles/a-record/
An A record maps a domain name to the IP address (IPv4) of the computer hosting the domain. Simply put, an A record is used to find the IP address of a computer connected to the internet from a name.

SOURCE

https://support.dnsimple.com/articles/a-record/

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All email services are based on which software model?

All email services are based on which software model?

• SMTP
• Client/server
• POP3
• TCP 

 

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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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 

 

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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