Symptom:
Invalid characters as well as invalid names and ip addresses are accepted as parameters in the following cli:
ip domain-name
ip domain-list
ip name-server

This will cause removal of some of these cli to display error:
Error in saving name servers - invalid address
Cannot write dns configuration

Conditions:
Set "ip domain-name", "ip domain-list", "ip name-server" to use invalid characters in the names and invalid ip addresses in the name-servers.