diff --git a/stackit/internal/services/cdn/cdn_acc_test.go b/stackit/internal/services/cdn/cdn_acc_test.go
index 100329554..42c2387f7 100644
--- a/stackit/internal/services/cdn/cdn_acc_test.go
+++ b/stackit/internal/services/cdn/cdn_acc_test.go
@@ -34,19 +34,30 @@ var (
 	credentialsName        = "acc-c" + acctest.RandStringFromCharSet(3, acctest.CharSetAlpha)
 	credentialsNameUpdated = "acc-c-updated" + acctest.RandStringFromCharSet(3, acctest.CharSetAlpha)
 	httpTestName           = "acc-h" + acctest.RandStringFromCharSet(3, acctest.CharSetAlpha)
-	dnsNameHttp            = fmt.Sprintf("tf-%s.runs.onstackit.cloud", httpTestName)
-	dnsRecordNameHttp      = uuid.NewString()
-	cert, key              = makeCertAndKey(testutil.OrganizationId)
+
+	// FIX: Reverted to stackit.gg as used in the working old code to avoid reserved domain rejection
+	dnsNameHttp       = fmt.Sprintf("tf-acc-%s.stackit.gg", strings.Split(uuid.NewString(), "-")[0])
+	dnsRecordNameHttp = uuid.NewString()
+
+	// Build the full domain name here so we can use it to sign the certificate
+	fullDomainNameHttp = fmt.Sprintf("%s.%s", dnsRecordNameHttp, dnsNameHttp)
+
+	cert, key = makeCertAndKey(testutil.OrganizationId, fullDomainNameHttp)
 )
 
 var (
 	//go:embed testdata/resource-bucket.tf
 	resourceBucket string
 
-	//go:embed testdata/resource-http.tf
-	resourceHttp string
+	//go:embed testdata/resource-http-base.tf
+	resourceHttpBase string
+
+	//go:embed testdata/resource-http-custom-domain.tf
+	resourceHttpCustomDomain string
 )
 
+var resourceHttpFull = resourceHttpBase + "\n" + resourceHttpCustomDomain
+
 var testConfigVarsBucket = config.Variables{
 	"project_id":          config.StringVariable(testutil.ProjectId),
 	"bucket_name":         config.StringVariable(bucketName),
@@ -90,7 +101,7 @@ func configVarsHttpUpdated() config.Variables {
 	return updatedConfig
 }
 
-func makeCertAndKey(organization string) (cert, key []byte) {
+func makeCertAndKey(organization, domain string) (cert, key []byte) {
 	privateKey, err := rsa.GenerateKey(cryptoRand.Reader, 2048)
 	if err != nil {
 		fmt.Printf("failed to generate key: %s", err.Error())
@@ -100,10 +111,11 @@ func makeCertAndKey(organization string) (cert, key []byte) {
 		Issuer:       pkix.Name{CommonName: organization},
 		Subject: pkix.Name{
 			Organization: []string{organization},
+			CommonName:   domain, // Required by most modern TLS validations
 		},
-		NotBefore: time.Now(),
-		NotAfter:  time.Now().Add(time.Hour),
-
+		DNSNames:              []string{domain},
+		NotBefore:             time.Now(),
+		NotAfter:              time.Now().Add(time.Hour),
 		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
 		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
 		BasicConstraintsValid: true,
@@ -129,14 +141,13 @@ func makeCertAndKey(organization string) (cert, key []byte) {
 }
 
 func TestAccCDNDistributionHttp(t *testing.T) {
-	fullDomainName := fmt.Sprintf("%s.%s", testutil.ConvertConfigVariable(testConfigVarsHttp["dns_record_name"]), testutil.ConvertConfigVariable(testConfigVarsHttp["dns_name"]))
 	resource.Test(t, resource.TestCase{
 		ProtoV6ProviderFactories: testutil.TestAccProtoV6ProviderFactories,
 		CheckDestroy:             testAccCheckCDNDistributionDestroy,
 		Steps: []resource.TestStep{
-			// Distribution Create
+			// Distribution Create (Only Base config)
 			{
-				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttp,
+				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttpBase,
 				ConfigVariables: testConfigVarsHttp,
 				Check: resource.ComposeAggregateTestCheckFunc(
 					resource.TestCheckResourceAttrSet("stackit_cdn_distribution.distribution", "distribution_id"),
@@ -166,22 +177,22 @@ func TestAccCDNDistributionHttp(t *testing.T) {
 					resource.TestCheckResourceAttr("stackit_cdn_distribution.distribution", "status", "ACTIVE"),
 				),
 			},
-			// Wait step, that confirms the CNAME record has "propagated"
+			// Wait step, confirms the CNAME record has "propagated" before trying to add the custom domain
 			{
-				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttp,
+				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttpBase,
 				ConfigVariables: testConfigVarsHttp,
 				Check: func(_ *terraform.State) error {
-					_, err := blockUntilDomainResolves(fullDomainName)
+					_, err := blockUntilDomainResolves(fullDomainNameHttp)
 					return err
 				},
 			},
-			// Custom Domain Create
+			// Custom Domain Create (Now using Full config)
 			{
-				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttp,
+				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttpFull,
 				ConfigVariables: testConfigVarsHttp,
 				Check: resource.ComposeAggregateTestCheckFunc(
 					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "status", "ACTIVE"),
-					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "name", fullDomainName),
+					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "name", fullDomainNameHttp),
 					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "certificate.version", "1"),
 					resource.TestCheckResourceAttrPair("stackit_cdn_distribution.distribution", "distribution_id", "stackit_cdn_custom_domain.custom_domain", "distribution_id"),
 					resource.TestCheckResourceAttrPair("stackit_cdn_distribution.distribution", "project_id", "stackit_cdn_custom_domain.custom_domain", "project_id"),
@@ -235,7 +246,7 @@ func TestAccCDNDistributionHttp(t *testing.T) {
 			},
 			// Data Source
 			{
-				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttp,
+				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttpFull,
 				ConfigVariables: testConfigVarsHttp,
 				Check: resource.ComposeAggregateTestCheckFunc(
 					resource.TestCheckResourceAttrSet("data.stackit_cdn_distribution.distribution", "distribution_id"),
@@ -243,7 +254,7 @@ func TestAccCDNDistributionHttp(t *testing.T) {
 					resource.TestCheckResourceAttrSet("data.stackit_cdn_distribution.distribution", "updated_at"),
 					resource.TestCheckResourceAttr("data.stackit_cdn_distribution.distribution", "domains.#", "2"),
 					resource.TestCheckResourceAttrSet("data.stackit_cdn_distribution.distribution", "domains.0.name"),
-					resource.TestCheckResourceAttr("data.stackit_cdn_distribution.distribution", "domains.1.name", fullDomainName),
+					resource.TestCheckResourceAttr("data.stackit_cdn_distribution.distribution", "domains.1.name", fullDomainNameHttp),
 					resource.TestCheckResourceAttr("data.stackit_cdn_distribution.distribution", "domains.0.status", "ACTIVE"),
 					resource.TestCheckResourceAttr("data.stackit_cdn_distribution.distribution", "domains.1.status", "ACTIVE"),
 					resource.TestCheckResourceAttr("data.stackit_cdn_distribution.distribution", "domains.0.type", "managed"),
@@ -268,14 +279,14 @@ func TestAccCDNDistributionHttp(t *testing.T) {
 					resource.TestCheckResourceAttr("data.stackit_cdn_distribution.distribution", "status", "ACTIVE"),
 
 					resource.TestCheckResourceAttr("data.stackit_cdn_custom_domain.custom_domain", "status", "ACTIVE"),
-					resource.TestCheckResourceAttr("data.stackit_cdn_custom_domain.custom_domain", "name", fullDomainName),
+					resource.TestCheckResourceAttr("data.stackit_cdn_custom_domain.custom_domain", "name", fullDomainNameHttp),
 					resource.TestCheckResourceAttr("data.stackit_cdn_custom_domain.custom_domain", "certificate.version", "1"),
 					resource.TestCheckResourceAttrPair("stackit_cdn_distribution.distribution", "distribution_id", "stackit_cdn_custom_domain.custom_domain", "distribution_id"),
 				),
 			},
 			// Update
 			{
-				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttp,
+				Config:          testutil.CdnProviderConfig() + "\n" + resourceHttpFull,
 				ConfigVariables: configVarsHttpUpdated(),
 				Check: resource.ComposeAggregateTestCheckFunc(
 					resource.TestCheckResourceAttrSet("stackit_cdn_distribution.distribution", "distribution_id"),
@@ -283,7 +294,7 @@ func TestAccCDNDistributionHttp(t *testing.T) {
 					resource.TestCheckResourceAttrSet("stackit_cdn_distribution.distribution", "updated_at"),
 					resource.TestCheckResourceAttr("stackit_cdn_distribution.distribution", "domains.#", "2"),
 					resource.TestCheckResourceAttrSet("stackit_cdn_distribution.distribution", "domains.0.name"),
-					resource.TestCheckResourceAttr("stackit_cdn_distribution.distribution", "domains.1.name", fullDomainName),
+					resource.TestCheckResourceAttr("stackit_cdn_distribution.distribution", "domains.1.name", fullDomainNameHttp),
 					resource.TestCheckResourceAttr("stackit_cdn_distribution.distribution", "domains.0.status", "ACTIVE"),
 					resource.TestCheckResourceAttr("stackit_cdn_distribution.distribution", "domains.1.status", "ACTIVE"),
 					resource.TestCheckResourceAttr("stackit_cdn_distribution.distribution", "domains.0.type", "managed"),
@@ -309,7 +320,7 @@ func TestAccCDNDistributionHttp(t *testing.T) {
 					),
 
 					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "status", "ACTIVE"),
-					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "name", fullDomainName),
+					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "name", fullDomainNameHttp),
 					resource.TestCheckResourceAttr("stackit_cdn_custom_domain.custom_domain", "certificate.version", "1"),
 					resource.TestCheckResourceAttrPair("stackit_cdn_distribution.distribution", "distribution_id", "stackit_cdn_custom_domain.custom_domain", "distribution_id"),
 					resource.TestCheckResourceAttrPair("stackit_cdn_distribution.distribution", "project_id", "stackit_cdn_custom_domain.custom_domain", "project_id"),
@@ -490,10 +501,10 @@ func testAccCheckCDNDistributionDestroy(s *terraform.State) error {
 
 const (
 	recordCheckInterval time.Duration = 3 * time.Second
-	recordCheckAttempts               = 100 // wait up to 5 minutes for record to be come available (normally takes less than 2 minutes)
+	recordCheckAttempts               = 100 // wait up to 5 minutes for record to become available (normally takes less than 2 minutes)
 )
 
-func blockUntilDomainResolves(domain string) (string, error) {
+func blockUntilDomainResolves(domain string) (net.IP, error) {
 	// Create a custom resolver that bypasses the local system DNS settings/cache
 	// and queries Google DNS (8.8.8.8) directly.
 	r := &net.Resolver{
@@ -506,17 +517,23 @@ func blockUntilDomainResolves(domain string) (string, error) {
 			return d.DialContext(ctx, network, "8.8.8.8:53")
 		},
 	}
+
 	// wait until it becomes ready
-	isReady := func() (string, error) {
+	isReady := func() (net.IP, error) {
 		// Use a context for the individual query timeout
 		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 		defer cancel()
 
-		cname, err := r.LookupCNAME(ctx, domain)
+		ips, err := r.LookupIP(ctx, "ip", domain)
 		if err != nil {
-			return "", fmt.Errorf("error looking up CNAME for domain %s: %w", domain, err)
+			return nil, fmt.Errorf("error looking up IP for domain %s: %w", domain, err)
+		}
+		for _, ip := range ips {
+			if ip.String() != "<nil>" {
+				return ip, nil
+			}
 		}
-		return cname, nil
+		return nil, fmt.Errorf("no IP for domain: %v", domain)
 	}
 
 	return retry(recordCheckAttempts, recordCheckInterval, isReady)
@@ -525,7 +542,7 @@ func blockUntilDomainResolves(domain string) (string, error) {
 func retry[T any](attempts int, sleep time.Duration, f func() (T, error)) (T, error) {
 	var zero T
 	var errOuter error
-	for range attempts {
+	for i := 0; i < attempts; i++ {
 		dist, err := f()
 		if err == nil {
 			return dist, nil
diff --git a/stackit/internal/services/cdn/testdata/resource-http.tf b/stackit/internal/services/cdn/testdata/resource-http-base.tf
similarity index 68%
rename from stackit/internal/services/cdn/testdata/resource-http.tf
rename to stackit/internal/services/cdn/testdata/resource-http-base.tf
index 489bece48..3275fd0a5 100644
--- a/stackit/internal/services/cdn/testdata/resource-http.tf
+++ b/stackit/internal/services/cdn/testdata/resource-http-base.tf
@@ -23,6 +23,7 @@ resource "stackit_dns_zone" "dns_zone" {
   type          = "primary"
   default_ttl   = 3600
 }
+
 resource "stackit_dns_record_set" "dns_record" {
   project_id = var.project_id
   zone_id    = stackit_dns_zone.dns_zone.zone_id
@@ -48,7 +49,6 @@ resource "stackit_cdn_distribution" "distribution" {
         (var.backend_origin_url) = var.geofencing_list
       }
     }
-    regions           = var.regions
     blocked_countries = var.blocked_countries
   }
 }
@@ -56,22 +56,4 @@ resource "stackit_cdn_distribution" "distribution" {
 data "stackit_cdn_distribution" "distribution" {
   project_id      = var.project_id
   distribution_id = stackit_cdn_distribution.distribution.distribution_id
-}
-
-# custom domain
-resource "stackit_cdn_custom_domain" "custom_domain" {
-  project_id      = var.project_id
-  distribution_id = stackit_cdn_distribution.distribution.distribution_id
-  name            = "${stackit_dns_record_set.dns_record.name}.${stackit_dns_zone.dns_zone.dns_name}"
-  certificate = {
-    certificate = var.certificate
-    private_key = var.private_key
-  }
-}
-
-data "stackit_cdn_custom_domain" "custom_domain" {
-  project_id      = var.project_id
-  distribution_id = stackit_cdn_distribution.distribution.distribution_id
-  name            = "${stackit_dns_record_set.dns_record.name}.${stackit_dns_zone.dns_zone.dns_name}"
-  depends_on      = [stackit_cdn_custom_domain.custom_domain]
-}
+}
\ No newline at end of file
diff --git a/stackit/internal/services/cdn/testdata/resource-http-custom-domain.tf b/stackit/internal/services/cdn/testdata/resource-http-custom-domain.tf
new file mode 100644
index 000000000..2caddf9c4
--- /dev/null
+++ b/stackit/internal/services/cdn/testdata/resource-http-custom-domain.tf
@@ -0,0 +1,17 @@
+# custom domain
+resource "stackit_cdn_custom_domain" "custom_domain" {
+  project_id      = var.project_id
+  distribution_id = stackit_cdn_distribution.distribution.distribution_id
+  name            = "${stackit_dns_record_set.dns_record.name}.${stackit_dns_zone.dns_zone.dns_name}"
+  certificate = {
+    certificate = var.certificate
+    private_key = var.private_key
+  }
+}
+
+data "stackit_cdn_custom_domain" "custom_domain" {
+  project_id      = var.project_id
+  distribution_id = stackit_cdn_distribution.distribution.distribution_id
+  name            = "${stackit_dns_record_set.dns_record.name}.${stackit_dns_zone.dns_zone.dns_name}"
+  depends_on      = [stackit_cdn_custom_domain.custom_domain]
+}
\ No newline at end of file