CIDRs and OCI Virtual Cloud Networks

Recently, someone preparing for the Oracle Cloud Infrastructure Networking Professional Certification approached me with a query:

From the provided options the only correct answer is 192.168.0.0/16. And this is pretty obvious that 8.8.8.8/8 and 189.215.154.89/32 are incorrect options. However, he was puzzled as to why the prefixes 10.0.0.0 and 172.16.0.0 were considered incorrect, given that they are supposed to be part of the reserved ranges for private IP addresses.

Indeed, they are. And Oracle recommends using the private IP address ranges specified in RFC 1918, which reserves and recommends the following three blocks of the IP address space for private internet addresses:

• 10.0.0.0/8
• 172.16.0.0/12
• 192.168.0.0/16

The issue here lies in the range.

Therefore:

• 10.0.0.0/16 is used instead of 10.0.0.0/8.
• 172.16.0.0/16 is used instead of 172.16.0.0/12.
• 192.168.0.0/16 is supported.

Let’s wrap up with a piece of advice.

It’s important to note that having two overlapping CIDR ranges within an Oracle Cloud Infrastructure (OCI) Virtual Cloud Network (VCN) is not considered a good practice. Overlapping CIDR ranges can lead to network communication issues and routing conflicts, potentially causing disruptions in connectivity and overall network performance. It’s advisable to carefully plan and allocate non-overlapping CIDR ranges for different VCNs or subnets to ensure efficient network management and seamless communication within the OCI environment.

Oracle Database 11g SQL (Oracle Press)

(69)

$51.01 (as of December 20, 2024 21:38 GMT +00:00 - More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)

Oracle 19c on Red Hat 8: Stand-Alone, Dataguard, Cluster RAC 2 nodes

(2)

$16.00 (as of December 20, 2024 21:38 GMT +00:00 - More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)

Create Rapid Low-Code Web Applications in Oracle APEX 21.2: A platform to develop stunning, scalable data-centric web apps fast

(12)

$35.00 (as of December 20, 2024 21:38 GMT +00:00 - More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)

The New Imperialists

(8)

$3.21 (as of December 20, 2024 21:38 GMT +00:00 - More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)