Friday, January 24, 2014

The quizzer

The script outlined below is essentially a set of electronic flash cards. There are all sorts of websites & programs that offer similar functionality.  That being said, I had a large set of terms I wanted to memorize, and this seemed like a fun way to get a little more Powershell experience.  

Many parts of the script are VERY basic, but there were a few parts (Get-Random and hash tables) that were interesting to explore.  

Here is an overview of the components of the script:

1) Read in a CSV of terms and definitions
2) Randomly pick a Term / Definition to quiz the user on
3) Generate a hash of the correct term (answer) and 4 other false answers
4) Randomize the hash and present to the user
5) Prompt the user to select an answer and evaluate the response

Click here for the full script



Saturday, January 18, 2014

Faster DNS Resolution

Recently a friend shared a link from TechRepublic that suggested changing your DNS servers in order improve web browsing speeds.

This seemed interesting and I initially changed my home DNS servers to 8.8.8.8 and 8.8.4.4.  Afterward, I started to wonder if my Internet provider might be able to route to one DNS server faster than another.  Additionally, it seemed logical to assume that the actual resolution could potentially be done faster on one DNS server farm than another.

It seemed like it would be neat to validate existing performance vs. the suggested DNS servers listed in the TechRepublic article.  The idea would be to highlight if a DNS server change would be beneficial on your home network.

Here is the type of output I ended up with:

10.10.1.1 is an internal DNS server and should not be modified
10.10.1.2 is an internal DNS server and should not be modified

Resolution times by DNS Servers (best to worst)

Name              Value
208.67.222.222    00:00:00.0728325
75.75.75.75*      00:00:00.0740533
208.67.220.220    00:00:00.0813375
8.8.8.8           00:00:00.0988982
8.8.4.4           00:00:00.1096580                                                                                      
* - denotes your existing DNS server

If you would like to test your current DNS settings, you are welcome to try the following powershell script on your system:

$ErrorActionPreference = "SilentlyContinue"
cls
$DNS = Get-WmiObject Win32_NetworkAdapterConfiguration -computername . | select DNSServerSearchOrder
$names = $dns.DNSServerSearchOrder
$techRepublicSuggested = ("208.67.222.222", "208.67.220.220", "8.8.8.8", "8.8.4.4")
$names = $names + $techRepublicSuggested
Foreach ($name in $names)
    {
    if (($name -like "10.*") -or ($name -like "176.*") -or ($name -like "192.168.*"))
        {
        Write-Host "$name is an internal DNS server and should not be modified"
        $names =  $names -replace $name
        }
    }
Write-Host ""
$names = $names | Where { $_.Trim(" `t")}
$hashlatency = @{}
$hashresolve = @{}
Foreach ($name in $names)
    {
    $resTime = Measure-command {resolve-dnsname systemzengineer.blogspot.com -server $name}
    if ($techRepublicSuggested -notcontains $name)
        {$name = $name + "*"}
    $hashresolve.add($name, $resTime)
    }
Write-Host "Resolution times by DNS Servers (best to worst)"
$hashresolve.GetEnumerator() | Sort-Object Value
Write-Host ""
Write-Host "* - denotes your existing DNS server"