What date/time is UNIX time calculated based off of?

What date/time is UNIX time calculated based off of?

• 00:00:00 31 December 1967
• 00:00:00 1 January 0000
• 00:00:00 1 January, 1900
• 00:00:00 1 January 1970 

 

EXPLANATION

 

Epoch time, also known as Unix time, is defined as the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970 (not counting leap seconds).

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Which Symbol denotes an ID in CSS?

Which Symbol denotes an ID in CSS?

• .
• %
• $
• #

EXPLANATION

The #id selector styles the element with the specified id.
CSS Syntax:

#id {
    css declarations;
}

http://www.htmldog.com/guides/css/intermediate/classid/

 

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Why is the Power Factor (PFC) value listed on most modern PSU units?

Why is the Power Factor (PFC) value listed on most modern PSU units?

• It indicates the level of efficiency of the PSU
• It points to the materials used in the PSU (Gold, Silver etc)
• It relates with the thermal resistance properties
• Indicates coeficient for the longevity of the PSU 

 

EXPLANATION

The Power Factor value shows the efficiency of the power unit. The power unit capabilities are usually stated as W consumed by the unit (kVA). How much of this power will be available to the loads attached to the PSU however is dictated by the its conversion capabilities summarized by the PFC value. For example, a 1000W PSU with a PFC factor of 0.9 will be able to supply a total of 900W to it's loads.

The PFC itself measures the alignment of the the voltage sinusoidal against the current sinusoidal. If they match 100% you would get a PFC of 1 and hence the perfect lossless PSU. In realty >0.95 is hardly achieved and considered very good while 0.8 could be considered as average PSU. 0.7 is considered as a bad performing PSU

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Which of the following CLI commands empties the DNS server cache in Windows Server?

Which of the following CLI commands empties the DNS server cache in Windows Server?

• ipconfig /flushdns
• Set-DNS -ClearCache
• Delete-DNSCache
• dnscmd /clearcache 

 EXPLANATION Dnscmd /clearcache clears the cache used for DNS server. Dnscmd is the tool used to manage DNS from the command line.
ipconfig /flushdns clears the DNS client cache. A DNS server has both caches but the client cache is the one used to provide name resolution for its own requests, not for other clients on the network.
Dnscmd TechNet article:
https://technet.microsoft.com/en-us/library/cc772069(v=ws.11).aspx

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What type of malware replicates itself from PC to PC throughout the network?

What type of malware replicates itself from PC to PC throughout the network?

• Spyware
• Scareware/ransomware
• Trojan
• Worm

EXPLANATION

Computer worms use the network to send copies of themselves to other PCs, usually exploiting a security hole to travel from one host to the next without user intervention. Because they can spread so rapidly across a network infecting every PC in their path, they tend to be the most well-known type of malware, although many users still mistakenly refer to them as viruses.
Trojan horses are applications that look like they are doing something innocuous, but secretly have malicious code that does something else. In many cases, trojans will create a backdoor that allows your PC to be remotely controlled, either directly or as part of a botnet—a network of computers also infected with a trojan or other malicious software. The major difference between a virus and a trojan is that trojans don't replicate themselves—they must be installed by an unwitting user.

Scareware is a relatively new type of attack, where a user is tricked into downloading what appears to be an antivirus application, which then proceeds to tell you that your PC is infected with hundreds of viruses that can only be cleaned if you pay for a full license. Of course, these scareware applications are nothing more than malware that hold your PC hostage until you pay the ransom—in most cases, you can't uninstall them or even use the PC.



Spyware is any software installed on your PC that collects your information without your knowledge, and sends that information back to the creator so they can use it in some nefarious way. This could include keylogging to learn your passwords, watching your searching habits, changing out your browser home and search pages, adding obnoxious browser toolbars, or just stealing your passwords and credit card numbers.

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Revoked digital certificates are listed in a(n)

Revoked digital certificates are listed in a(n)

• Public Key Crypto Folder (PKCF)
• Certificate Revocation List (CRL)
• 509.X certificate
• Certification Authority Revocation Algorithm (CARA) 

EXPLANATION

n the operation of some cryptosystems, usually public key infrastructures (PKIs), a certificate revocation list (CRL) is a list of certificates
dhruv-k@hcl.com (or more specifically, a list of serial numbers for certificates) that have been revoked, and therefore, entities presenting those (revoked) certificates should no longer be trusted.
https://en.wikipedia.org/wiki/Revocation_list

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What type of jack would you normally use for a POTS line?

What type of jack would you normally use for a POTS line?

• RJ9
• RJ31X
• RJ11
• RJ45 

 

EXPLANATION

An RJ11 jack supports one POTS (Plain Old Telephone Service) line.
An RJ9 is an unofficial 4P4C plug that is sometimes used for the handset connection to the telephone.  Think the coiled cord. (http://blog.jabra.com/4-types-of-wired-headset-connectors/)
An RJ31X is a special type of jack that can accommodate up to two POTS lines, but is wired using 4 pairs of wire.  This can be described as an intercept or "Man in the Middle" plug.  It is most commonly used with alarm systems,  When the alarm panel is plugged into the jack, the POTS lines pass through the alarm system.  This allow the alarm system to seize the line, possibly dropping a call in progress.  When the alarm system is not plugged into the jack, the POTS lines work normally.

An RJ45 is the jack most IT people are familiar with.  It is the 4 pair plug we normally associate with ethernet and patch cables.

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