Validate and document Dynu-rejected documentation IP ranges

internal/provider/resource_dns_record.go

@@ -478,6 +478,13 @@ func validateDNSRecordContentForTypeWithKnowledge(recordType string, content *st
 			diagnostics.AddError("Invalid DNS record content", fmt.Sprintf("Record type %q requires an IPv6 address, got %q.", normalizedType, trimmedContent))
 			return false
 		}
+		if isDocumentationAddress(addr) {
+			diagnostics.AddError(
+				"Unsupported documentation IP address",
+				fmt.Sprintf("Dynu rejects documentation-only address ranges for live DNS records. Replace %q with a real routable address under your control.", trimmedContent),
+			)
+			return false
+		}
 		return true
 	}
 
@@ -504,6 +511,22 @@ func validateDNSRecordContentForTypeWithKnowledge(recordType string, content *st
 	return true
 }
 
+func isDocumentationAddress(addr netip.Addr) bool {
+	if addr.Is4() {
+		v4 := addr.As4()
+		return (v4[0] == 192 && v4[1] == 0 && v4[2] == 2) ||
+			(v4[0] == 198 && v4[1] == 51 && v4[2] == 100) ||
+			(v4[0] == 203 && v4[1] == 0 && v4[2] == 113)
+	}
+
+	if addr.Is6() {
+		v6 := addr.As16()
+		return v6[0] == 0x20 && v6[1] == 0x01 && v6[2] == 0x0d && v6[3] == 0xb8
+	}
+
+	return false
+}
+
 func resolveDynamicIntent(recordType string, content types.String, dynamic types.Bool, diagnostics *diag.Diagnostics) (bool, bool) {
 	normalizedType := strings.ToUpper(strings.TrimSpace(recordType))
 	contentPtr := stringPointerFromOptionalContent(content)

internal/provider/resource_dns_record_integration_test.go

@@ -195,7 +195,7 @@ func TestIntegrationResourceDNSRecordDynamicAStateStableAndTransitionToStatic(t
 	}
 
 	updatePlan := state
-	updatePlan.Content = types.StringValue("192.0.2.42")
+	updatePlan.Content = types.StringValue("1.1.1.1")
 	updatePlan.Dynamic = types.BoolValue(false)
 
 	plan = tfsdk.Plan{Schema: schemaResp.Schema}
@@ -214,7 +214,7 @@ func TestIntegrationResourceDNSRecordDynamicAStateStableAndTransitionToStatic(t
 	if state.Dynamic.ValueBool() {
 		t.Fatalf("expected static A after setting content")
 	}
-	if state.Content.ValueString() != "192.0.2.42" {
+	if state.Content.ValueString() != "1.1.1.1" {
 		t.Fatalf("expected static content after update, got %q", state.Content.ValueString())
 	}
 }

internal/provider/resource_dns_record_test.go

@@ -26,8 +26,8 @@ func TestParseDNSRecordIDInvalid(t *testing.T) {
 }
 
 func TestValidateDNSRecordContentForType(t *testing.T) {
-	ipv4 := "192.0.2.123"
-	ipv6 := "2001:db8::123"
+	ipv4 := "8.8.8.8"
+	ipv6 := "2606:4700:4700::1111"
 	nonEmpty := "hello"
 	blank := ""
 
@@ -75,7 +75,7 @@ func TestResolveDynamicIntent(t *testing.T) {
 	}
 
 	diags = diag.Diagnostics{}
-	dynamic, ok = resolveDynamicIntent("A", types.StringValue("192.0.2.10"), types.BoolNull(), &diags)
+	dynamic, ok = resolveDynamicIntent("A", types.StringValue("8.8.4.4"), types.BoolNull(), &diags)
 	if !ok || dynamic || diags.HasError() {
 		t.Fatalf("expected static A content to resolve to dynamic=false, got dynamic=%v ok=%v diags=%v", dynamic, ok, diags)
 	}