Domains can be delegated to OCI DNS from the Domain Registrar's self-service portal. The explanation is that delegating a domain to OCI DNS means that you are transferring the authority to resolve DNS queries for your domain from your current DNS provider to OCI DNS. To delegate a domain to OCI DNS, you need to create a zone in OCI DNS that matches your domain name and add any records that you want to serve from OCI DNS. Then, you need to update the name servers for your domain at your Domain Registrar's self-service portal with the name servers provided by OCI DNS. This will point your domain to OCI DNS and allow it to resolve DNS queries for your domain.

Explanation
Ensure VCN CIDR prefix overlaps with other VCNs in your tenancy or with your organizations private IP network ranges. The explanation is that a VCN CIDR prefix is the range of IPv4 addresses that can be used within the VCN and its subnets. The VCN CIDR prefix should not overlap with other VCNs in your tenancy or with your organization's private IP network ranges, as this can cause routing conflicts and connectivity issues. You should choose a VCN CIDR prefix that is large enough to accommodate your current and future needs, but not too large to waste IP addresses. You can use any of the private IPv4 address ranges specified in RFC 1918 for your VCN CIDR prefix.

The explanation is that burstable instances are VM instances that have a baseline utilization of either 12% or 50% of each CPU core, not 25% or 75%. Burstable instances are designed for scenarios where an instance is typically idle or has low CPU utilization but occasionally needs to burst above the baseline to handle spikes in demand. Burstable instances cost less than regular instances with the same total OCPU count but charge extra for bursting above the baseline OCPU.

Explanation
If you choose not to proactively reboot the instance before the scheduled maintenance due date, the instance is either reboot-migrated or rebuilt in place for you. Reboot-migration is a process where OCI migrates your instance to a new physical host without changing its configuration or public IP address. Rebuild in place is a process where OCI shuts down your instance, performs maintenance on the physical host, and restarts your instance with the same configuration and public IP address. The other options are not correct. References:
[Reboot-Migration], [Rebuild in Place]

Explanation
Create a replication policy to send data to a different bucket in another OCI region. The explanation is that replication is a feature of Object Storage that allows you to automatically copy objects from one bucket to another bucket, either in the same region or in a different region. Replication can help you improve data availability and durability, as well as meet compliance and disaster recovery requirements. To enable replication, you need to create a replication policy that specifies the source and destination buckets, the replication frequency, and the replication filters. Replication policies are evaluated every five minutes and copy any new or updated objects from the source bucket to the destination bucket.