In IT, the term kilobyte (KB) is traditionally used to connote which of the following?

In IT, the term kilobyte (KB) is traditionally used to connote which of the following?

• 10000 bytes
• 1024 bytes
• 512 bytes
• 2048 bytes 

 

EXPLANATION

Because computers are binary (base 2) instead of decimal (base 10), 1KB would be 2 to the 10th bytes, or 1024.

In fact, the definition of KB (kilobytes) was changed in 1998 to match up with SI units, the current term for 1024 bytes is Kibibyte (https://en.wikipedia.org/wiki/Kibibyte). That said, most IT pros still prefer the traditional definition of KB as 1024 bytes, since it's the most common way to refer to computing capacity.

For further information about these terms, see http://www.iec.ch/si/binary.htm andhttp://physics.nist.gov/cuu/Units/binary.html

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What logic construct most efficiently allows you to execute one of a number of code blocks based on the value of a single variable?

What logic construct most efficiently allows you to execute one of a number of code blocks based on the value of a single variable?

• while
• if
• switch
• for 

EXPLANATION

You can supply a variable to a "switch" statement, and provide a code block for each possible value.
Example using PowerShell:

switch ($var) {
    1 { <# Executes if $var = 1 #> }
    2 { <# Executes if $var = 2 #> }
    3 { <# Executes if $var = 3 #> }
    4 { <# Executes if $var = 4 #> }
    default { <# Executes if $var doesn't match any other case #> }
}

A single "switch" can take the place of a chain of "if/elseif/else".
"for" and "while" are both loops.

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What can be used to protect you from receiving email messages with a forged sender address?

What can be used to protect you from receiving email messages with a forged sender address?

• SPF
• Secure SMTP
• Digital ID
• IMAP 

 

EXPLANATION

Sender Policy Framework (SPF) is a simple email-validation system designed to detect email spoofing by providing a mechanism to allow receiving mail exchangers to check that incoming mail from a domain comes from a host authorized by that domain's administrators.[1] The list of authorized sending hosts for a domain is published in the Domain Name System (DNS) records for that domain in the form of a specially formatted TXT record. Email spam and phishing often use forged "from" addresses, so publishing and checking SPF records can be considered anti-spam techniques.
IETF publication RFC 7208 dated April 2014 defines Sender Policy Framework as "proposed standard".

SOURCE

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

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What is the command to force Knowledge Consistency Checker (KCC) on targeted domain controllers to immediately recalculate the inbound replication topology.

What is the command to force Knowledge Consistency Checker (KCC) on targeted domain controllers to immediately recalculate the inbound replication topology.

• Repadmin -replicate
• Repadmin -prp
• Repadmin -showutdvec
• Repadmin -kcc 

 

EXPLANATION

This command helps repair broken connections between domain controllers by rebuilding the active connection.

SOURCE

https://technet.microsoft.com/en-us/library/cc770963(v=ws.11).aspx

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What is the difference between TACACS+ and RADIUS?

What is the difference between TACACS+ and RADIUS?

•  TACACS+ encrypts the entire packet and RADIUS does not.
• TACACS+ uses UDP transport protocol and RADIUS uses TCP.
• RADIUS is defined by Cisco and TACACS+ is RFC 2865.
• RADIUS encrypts the entire packet and TACACS+ does not. 

 

EXPLANATION

TACACS+ uses Transmission Control Protocol (TCP) port 49 to communicate between the TACACS+ client and the TACACS+ server. An example is a Cisco switch authenticating and authorizing administrative access to the switch’s IOS CLI. The switch is the TACACS+ client, and Cisco Secure ACS is the server.
One of the key differentiators of TACACS+ is its ability to separate authentication, authorization and accounting as separate and independent functions. This is why TACACS+ is so commonly used for device administration, even though RADIUS is still certainly capable of providing device administration AAA.
Device administration can be very interactive in nature, with the need to authenticate once, but authorize many times during a single administrative session in the command-line of a device. A router or switch may need to authorize a user’s activity on a per-command basis. TACACS+ is designed to accommodate that type of authorization need.   As the name describes, TACACS+ was designed for device administration AAA, to authenticate and authorize users into mainframe and Unix terminals, and other terminals or consoles.
TACACS+ communication between the client and server uses different message types depending on the function. In other words, different messages may be used for authentication than are used for authorization and accounting. Another very interesting point to know is that TACACS+ communication will encrypt the entire packet.

SOURCE

http://www.networkworld.com/article/2838882/radius-versus-tacacs.html

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