What is the number of bits in a nibble?

What is the number of bits in a nibble?

• 8 Bits
• 4 Bits
• 6 Bits
• 2 Bits 

EXPLANATION

multiply the digital storage value by 4

Each 1 or 0 in a binary number is called a bit. From there, a group of 4 bits is called a nibble, and 8-bits makes a byte. Bytes are a pretty common buzzword when working in binary. Processors are all built to work with a set length of bits, which is usually this length is a multiple of a byte: 8, 16, 32, 64, etc.

 

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What do applications use to communicate with the kernel?

What do applications use to communicate with the kernel?

• Shells
• System calls
• Shell scripts
• C programs 

 

EXPLANATION

In computing, a system call is the programmatic way in which a computer program requests a service from the kernel of the operating system it is executed on. This may include hardware-related services, creation and execution of new processes, and communication with integral kernel services such as process scheduling. System calls provide an essential interface between a process and the operating system.

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What Linux command would you use to figure out the path of an executable file?

What Linux command would you use to figure out the path of an executable file?

• where
• what
• which
• wexec 

EXPLANATION

Find the correct path to an executable file in Unix

Several Unix dialects use the whereis command to find where programs, or executables, are stored in the file structure of the computer. To use it at the Unix prompt, enter:

  whereis command

Replace command with the name of the executable for which you are looking. For example, if you are looking for the location of the lpr command, you would enter:

  whereis lpr

The whereis command will return something like the following:

  lpr: /usr/ucb/lpr /usr/man/man1/lpr.1

In this example, the query asked about the lpr command, which spools jobs to printers. The operating system returned two answers, and thus two paths. The first path is the location of the lpr executable, and the second path is the location of the lpr manual page.
To find the path the operating system uses to execute a command when you enter it on the command line, use the which command instead, for example:

  which lpr

This command will output something like the following:

  /var/bsd/lpr

This means that when you enter lpr at the command line, the system is really executing /var/bsd/lpr.

 

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If you’re looking to find out the size of each file in a given directory, what Linux command would you use?

If you’re looking to find out the size of each file in a given directory, what Linux command would you use?

• ls -i
• du
• ls -a
• ls -la 

 

EXPLANATION

du -sh file_path
 
Detail

• du (disc usage) command estimates file_path space usage
• The options -sh are (from man du):
  

    -s, --summarize
           display only a total for each argument
  
    -h, --human-readable
           print sizes in human readable format (e.g., 1K 234M 2G)

  To check more than one directory and see the total, use du -sch:
  

    -c, --total
           produce a grand total

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An LRU algorithm helps a program work with the computer's cache. What does LRU stand for?

An LRU algorithm helps a program work with the computer's cache. What does LRU stand for?

• Least recently usable
• Last received unit
• Least recently used
• Lost recovered unit 

EXPLANATION

LRU (Least Recently Used) Page replacement algorithm.

cache algorithms are optimizing instructionsor algorithmsthat a computer program or a hardware-maintained structure can follow in order to manage a cache of information stored on the computer. When the cache is full, the algorithm must choose which items to discard to make room for the new ones.

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What is the correct water temperature range to brew coffee at?

What is the correct water temperature range to brew coffee at?

• 175-185 (F) / 80-85 (C)
• 195-205 (F) / 90-96 (C)
• 208-212 (F) / 98-100 (C)
• 350-400 (F) / 175-205 (C)

EXPLANATION

The ideal temperature range for hot brewing is 195 to 205 degrees Fahrenheit. This is hot enough to extract carefully and quickly, but not so hot that it’s uncontrollable.

• Coffee over 205 degrees Fahrenheit tends to over extract things from the grounds very easily, producing bitter coffee.
• Water under 195 degrees has a difficult time extracting, which often leads to sour, underdeveloped coffee.

The 195 to 205 degree range isn’t the objective gold standard for water temperature for coffee brewing. It’s just the range that most people around the world tend to use the most because it tends to make the best, most balanced coffee. You are free to depart from this proven temperature range, but I don’t suggest it unless you’re a seasoned coffee veteran.
There are quite a few coffee professionals who use lower temperatures to achieve different results in their coffee. One World Aeropress Championship finalist in 2013 used water at 176 degrees. Another major figure in the coffee world commonly uses 190 degrees in his Aeropress recipe.
It can be done if you have master-level control of other coffee variables, but most of us like to stick to the tried and true, classic range of 195 to 205 degrees.

 

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If you experience a system failure, what’s the best way to recover your database?

If you experience a system failure, what’s the best way to recover your database?

• Rollback
• Switch to duplicate database
• Rollforward
• Reprocess transactions 

EXPLANATION

 1.

Recovery is needed when a database instance that has failed is restarted or a surviving database instance takes over a failed one. In roll-backward recovery, the active transactions at the time of failure are aborted and the resourced allocated for those transactions are released. In roll-forward recovery, the updates recorded in the redo log are transferred to the database so that they are not lost.

2.

Recovery is needed when a database instance that has failed is restarted or a surviving database instance takes over a failed one. In roll-backward recovery, the active transactions at the time of failure are aborted and the resourced allocated for those transactions are released. In roll-forward recovery, the updates recorded in the redo log are transferred to the database so that they are not lost.

3.

Recovery is needed when a database instance that has failed is restarted or a surviving database instance takes over a failed one. In roll-backward recovery, the active transactions at the time of failure are aborted and the resourced allocated for those transactions are released. In roll-forward recovery, the updates recorded in the redo log are transferred to the database so that they are not lost. 

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