This script had interest from an enterprising gent on a previous blog post that outlined what kind of tasks I've automated and reporting I gather from my environment.
Every morning at 6AM, my primary domain controller runs a comprehensive DCDIAG, and sends it to me. I use select-string to search the results of the DCDIAG output for the string "Failed". It's not foolproof; sometimes I do get failure emails (most of the time it's laggy replication caused by Veeam taking a backup snapshot). But I'd rather have advanced warning that something might be wrong with the most important thing in my environment: Active Directory.
As has become my custom, the comments do the talking from here on out.
#Specify some variables: the output file, what I'll search for, and email settings.
$TempFile = "C:\Temp\DCDiag_Temp.txt"
$SearchText = "Failed"
$SMTP = "mailserver.contoso.com"
$To = "email@example.com"
$From = "firstname.lastname@example.org"
#Run the DCDIAG with the following switches: Comprehensive, Enterprise (runs against all DCs)
#and verbose, outputting to file
DCDiag /c /e /v > $TempFile
#Read the File
$DCDiag = (Get-Content $TempFile)
#Look for the string, and count how many time it appears, then convert it to a string
#Then take out some newline characters
$FailCount = (($DCDiag | select-string -simple $SearchText | measure-object).count | out-string)
$FailCountString = ($FailCount | out-string)
$FailCountString = ($FailCountString.replace("`r`n",""))
#Format the email, placing a count of the term "Failed" in the subject
$Subject = "PS Report - DCDiag Error Report - $FailCountString Errors"
$Body = "$FailCountString Errors"
#Send me an email
Send-Mailmessage -from $From -to $To -subject $Subject -smtpserver $SMTP -body $Body -Attachments $TempFile
#Delete the temp file
Normally, I only send the email if there's something to report, but I send this one every day for two reasons. One, I like knowing that it's running, and two, it gives me a warm fuzzy feeling seeing that AD is healthy (almost) every morning.