Monitoring with PowerShell: Monitoring DNS record changes

Short one today, as I’m super busy with regular work. 🙂

At my company we use a dynamic DNS service for load balancing or failover. This is great because clients don’t notice downtime when a failover or load balancing action occurs. It makes everything smooth and fluent for clients and users of our systems.

The only problem with this is that sometimes a failover occurs and you don’t notice. Great for users, not so great for administrators; if a server crashes in the woods, did it really crash at all?

To make sure we always get notified about these situations we use the following script via our RMM system.

$DomainsToTest = @("remote.clientname.com", "clientswebsite.com")
New-item "C:\ProgramData\DNSTestLog" -ItemType Directory -erroraction SilentlyContinue -Force | out-null

$DNSHealth = foreach ($DomainToTest in $DomainsToTest) {

    Clear-DnsClientCache

    $PreviousDNS = get-content "C:\ProgramData\DNSTestLog\$($DomainToTest).txt" -ErrorAction SilentlyContinue
    if (!$PreviousDNS) {
        write-host "No previous file found. Creating file. Compare will fail."
        "" | Out-File "C:\ProgramData\DNSTestLog\$($DomainToTest).txt"
    }
    $DNSResults = (Resolve-dnsname -name $DomainToTest -Type A -NoHostsFile).IP4Address
    $DNSResults | Out-File "C:\ProgramData\DNSTestLog\$($DomainToTest).txt"
    if ($PreviousDNS -ne $DNSResults) {
        "$DomainToTest does not equal the previous result."
    }

}

if (!$DNSHealth) {
$DNSHealth = "Healthy"
}

And that’s it! as always, Happy PowerShelling

Recent Articles

The return of CyberDrain CTF

CyberDrain CTF returns! (and so do I!)

It’s been since september that I actually picked up a digital pen equivalent and wrote anything down. This was due to me being busy with life but also my side projects like CIPP. I’m trying to get back into the game of scripting and blogging about these scripts. There’s still so much to automate and so little time, right? ;)

Monitoring with PowerShell: Monitoring Acronis Backups

Intro

This is a monitoring script requested via Reddit, One of the reddit r/msp users wondered how they can monitor Acronis a little bit easier. I jumped on this because it happened pretty much at the same time that I was asked to speak at the Acronis CyberSummit so it kinda made sense to script this so I have something to demonstrate at my session there.

Monitoring with PowerShell: Monitoring VSS Snapshots

Intro

Wow! It’s been a while since I’ve blogged. I’ve just been so swamped with CIPP that I’ve just let the blogging go entirely. It’s a shame because I think out of all my hobbies it’s one I enjoy the most. It’s always nice helping others achieve their scripting target. I even got a couple of LinkedIn questions asking if I was done with blogging but I’m not. Writing always gives me some more piece of mind so I’ll try to catch up again. I know I’ve said that before but this time I’ll follow through. I’m sitting down right now and scheduling the release of 5 blogs in one go. No more whining and no more waiting.