If you have changed the name server for this service to another DNS server without disabling DNSSEC, name resolution will no longer be available with the cache DNS function which uses DNSSEC validation.
Therefore, use the following method to disable DNSSEC.

• If you have a contract for our Domain Management Service
  Disable the DNSSEC setting from the Domain Management Service setting screen using IIJ Service Online.
  Refer to "自社で用意したDNSサーバにDNSSECを設定する"(Japanese Only) in the ドメイン管理サービスマニュアル (Japanese Only) for the operation method.
  It takes several hours to disable the DNSSEC setting.
  * If you have already changed the DNS server, you cannot disable DNSSEC from the console screen of this service because CDS for this service can no longer be recognized.
  
• If you use another company's service to manage domains
  Delete DS records on the side of the company's service.