**Add-SecureSiteBinding** script has been created to provide the ability to add one or more domains to an IIS website each tied to a self-signed certificate providing SSL capabilities. The script contains three parts which I'll review, the full script can be found in the [Add-SecureSiteBindings Gist](GIST URL).

Add-SecureSiteBindings.ps1

#Requires -RunAsAdministrator

[CmdletBinding()]
Param (
    
    [Parameter(Mandatory = $true, 
        Position=0,
        HelpMessage = "Name of the IIS Site the new URLs should be associated to")]
    [ValidateNotNullOrEmpty()]
    [string]
    $SiteName,

    [Parameter(Mandatory = $true, 
        Position=1,    
        HelpMessage = "Comma delimited list of all URLs to add to the site")]
    [ValidateNotNullOrEmpty()]
    [string[]]
    $NewDnsNames,

    [Parameter(Mandatory = $false,
        Position=2,
        HelpMessage = "Password to be used to export and import the certificate. Will be converted into a Secure String")]
    [string]
    $CertPassphrase = "Password12345",
    
    [Parameter(Mandatory=$false,
        Position=3,
        HelpMessage="Port that the site bindings will be established on, defaults to 443.")]
    [string]
    $Port = "443"
)

<#
.SYNOPSIS
    THIS IS DUPLICATED FROM THE SITECORE DOCKER TOOLS MODULE AVAILABLE FROM https://sitecore.myget.org/feed/sc-powershell/package/nuget/SitecoreDockerTools

    Duplication was done to eliminate any 
    Adds a host entry to the system hosts file.
.DESCRIPTION
    Adds a host entry with the specified Hostname and IPAddress to the system hosts file (if it does not already exist).
    A backup of the current hosts file is taken before updating.
.PARAMETER Hostname
    The hostname to use for the entry.
.PARAMETER IPAddress
    The IP address to use for the entry. Default is 127.0.0.1.
.INPUTS
    None. You cannot pipe objects to Add-HostsEntry.
.OUTPUTS
    None. Add-HostsEntry does not generate any output.
.EXAMPLE
    PS C:\> Add-HostsEntry 'my.host.name'
#>
function Add-HostsEntry
{
    Param (
        [Parameter(Mandatory = $true, Position = 0)]
        [ValidateNotNullOrEmpty()]
        [string]
        $Hostname,

        [string]
        [ValidateNotNullOrEmpty()]
        $IPAddress = "127.0.0.1",

        [string]
        $Path = (Join-Path -Path $env:windir -ChildPath "system32\drivers\etc\hosts")
    )

    if (-not (Test-Path $Path)) {
        Write-Warning "No hosts file found, hosts have not been updated"
        return
    }

    # Create backup
    Copy-Item $Path "$Path.backup"
    Write-Verbose "Created backup of hosts file to $Path.backup"

    # Build regex match pattern
    $pattern = '^' + [Regex]::Escape($IPAddress) + '\s+' + [Regex]::Escape($HostName) + '\s*$'

    $hostsContent = @(Get-Content -Path $Path -Encoding UTF8)

    # Check if exists
    $existingEntries = $hostsContent -match $pattern
    if ($existingEntries.Count -gt 0) {
        Write-Verbose "Existing host entry found for $IPAddress with hostname '$HostName'"
        return
    }

    # Add it
    $hostsContent += "$IPAddress`t$HostName"

    $hostsContent | Out-File -FilePath $Path -Encoding utf8
    Write-Verbose "Host entry for $IPAddress with hostname '$HostName' has been added"
}

<#
.SYNOPSIS
    Following logic is a modification to the examples demonstrating New-IISSiteBinding command 
      at https://docs.microsoft.com/en-us/powershell/module/iisadministration/new-iissitebinding?view=windowsserver2022-ps 
    
    Creates Self-Signed certifacte for all DNS/hostnames provided and then adds the appropriate binding to the named IIS web application
.PARAMETER NewDnsNames
    REQUIRED, Comma delimited list of all URLs to add to the site
.PARAMETER SiteName
    REQUIRED, Name of the IIS Site the new URLs should be associated to
.PARAMETER CertPassword
    REQUIRED, Secure string of a password/phrase to secure the export and import of the self-signed certificate
.PARAMETER BindingPort
    OPTIONAL, Default is 443. Port that the site bindings will be established on.
.INPUTS
    None.
.OUTPUTS
    None.
.EXAMPLE
    PS C:\> Set-NewSiteBinding -NewDnsNames rainflytours.com,rainflyadbenture.com -SiteName rainflysites -CertPassword PassIsSecure
.EXAMPLE
    PS C:\> Set-NewSiteBinding rainflytours.com,rainflyadbenture.com rainflysites PassIsSecure
.EXAMPLE
    PS C:\> Set-NewSiteBinding rainflytours.com,rainflyadbenture.com rainflysites PassIsSecure -BindingPort 8080
#>
function Set-NewSiteBinding {
    Param (
        [Parameter(Mandatory = $true,
            Position = 0,
            HelpMessage = "Comma delimited list of all URLs to add to the site")]
        [ValidateNotNullOrEmpty()]
        [string[]]
        $NewDnsNames,

        [Parameter(Mandatory = $true,
            Position = 1,
            HelpMessage = "Name of the IIS Site the new URLs should be associated to")]
            [ValidateNotNullOrEmpty()]
            [string]
        $SiteName,

        [Parameter(Mandatory = $true, 
            Position = 2,
            HelpMessage = "Password used to export and import the certificate")]
            [ValidateNotNullOrEmpty()]
            [SecureString]
        $CertPassword,

        [Parameter(Mandatory=$false,
            HelpMessage = "Port that the site bindings will be established on, defaults to 443.")]
        [string]
        $BindingPort = "443"
    )

    Write-Host "Creating Self-Signed Certificate for: $NewDnsNames"
    $storeLocation = "Cert:\LocalMachine\My"
    $certificate = New-SelfSignedCertificate -DnsName $NewDnsNames -CertStoreLocation $storeLocation
    $thumbPrint = $certificate.Thumbprint
    $certificatePath = ("cert:\localmachine\my\" + $certificate.Thumbprint)
    
    Export-PfxCertificate -FilePath "C:\temp\temp.pfx" -Cert $certificatePath -Password $CertPassword
    Import-PfxCertificate -FilePath "C:\temp\temp.pfx" -CertStoreLocation "Cert:\LocalMachine\Root" -Password $securedString
    
    foreach ($url in $NewDnsNames) {
        $bindingInformation = "*:" + $BindingPort + ":" + $url
        Write-Host "IIS Binding '$bindingInformation' to be added to $SiteName"        
        New-IISSiteBinding -Name $SiteName `
            -BindingInformation $bindingInformation `
            -CertificateThumbPrint $thumbPrint `
            -CertStoreLocation $storeLocation `
            -Protocol https `
            -SslFlag "Sni" `
            -Force
    }
}

<#
.SYNOPSIS
   Simple control method that makes the calls to created the certificates and bind them to IIS via Set-NewSiteBinding
   Followed by a simple loop to add host file entries for all hostnames

   Parameters for the file are used within this method.
#>
function Add-SecureSiteBindings {
    $securedString = ConvertTo-SecureString -String $CertPassphrase -Force -AsPlainText
    Set-NewSiteBinding -NewDnsNames $NewDnsNames -SiteName $SiteName -CertPassword $securedString -BindingPort $Port

    $NewDnsNames | ForEach-Object{ Add-HostsEntry $_.Trim(); }
}

# Setup a log file to capture any messages at the location of the script
$logFilePath = Join-Path -path (Split-Path -Parent $MyInvocation.MyCommand.Path) -ChildPath "invoke-newsitebinding-$(Get-date -f 'yyyyMMddHHmmss').log";
Add-SecureSiteBindings *>&1 | Tee-Object $logFilePath