Known issues and limitations

This section details some of the limitations and known issues of DNS Services.

• 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.