---
name: dns-svcs-known-limitations
title: Known issues and limitations
description: This section details some of the limitations and known issues of DNS Services.
last-updated: 2025-04-15
---

> ## Documentation Index
> The table of contents for this documentation set is at https://cloud.ibm.com/docs/dns-svcs?format=markdown
> The index for all IBM Cloud docs is at: https://cloud.ibm.com/docs/llms.txt
> Use these files to discover more information as needed.

# Known issues and limitations
{: #limitations-known-issues}

This section details some of the limitations and known issues of DNS Services.
{: shortdesc}

* Resolvers cache permitted network details for a zone. The TTL for these cached details is typically 1 hour.
* A zone can have an arbitrary number of levels, but not fewer than two. For example, `ibm.austin.texas.example.com` is a valid zone name, but com is not.
* When creating a DNS zone it is not allowed to have numbers in the top level domain (TLD). This means a zone such as `example.com1` is not valid
* In custom resolvers, disabling all custom resolver locations at the same time may be possible, but is _not recommended_ when the custom resolver is enabled.
* DNS Services custom resolver platform metrics do not track secondary zone usage. This means that DNS queries made to a configured custom resolver for a secondary zone will not be counted in the reported metrics.
* The DNS resolver always looks for a record from the longest matching zone, even though the record might not exist in the longest matching zone but does exist in another non-longest matching zone.