https://kb.isc.org/article/AA-01491
"ICANN is in the process of introducing a new Key Signing Key (KSK) for the global root zone. BIND has multiple methods for managing DNSSEC trust anchors, with somewhat different behaviors. If the root key is configured using the managed-keys statement, or if the pre-configured root key is enabled by using dnssec-validation auto, then BIND can keep keys up to date automatically. Servers configured in this way will roll seamlessly to the new key when it is published in the root zone. However, keys configured using the trusted-keys statement are not automatically maintained. If your server is performing DNSSEC validation and is configured using trusted-keys, you are advised to change your configuration before the root zone begins signing with the new KSK. This is currently scheduled for October 11, 2017."
"ICANN is in the process of introducing a new Key Signing Key (KSK) for the global root zone. BIND has multiple methods for managing DNSSEC trust anchors, with somewhat different behaviors. If the root key is configured using the managed-keys statement, or if the pre-configured root key is enabled by using dnssec-validation auto, then BIND can keep keys up to date automatically. Servers configured in this way will roll seamlessly to the new key when it is published in the root zone. However, keys configured using the trusted-keys statement are not automatically maintained. If your server is performing DNSSEC validation and is configured using trusted-keys, you are advised to change your configuration before the root zone begins signing with the new KSK. This is currently scheduled for October 11, 2017."