DNS
20 BADNAME
Duplicate key name. The key name in a TKEY negotiation is already in use or conflicts with an existing key.
When You See This Code
A TKEY key establishment failed because a key with the same name already exists on the server from a previous session that was not properly cleaned up.
How to Fix
Use a unique key name for each TKEY session (e.g., append a timestamp or random suffix). Delete stale keys on the server if they are no longer needed.