Oracle Net Assistant was sunset after Oracle9i

Oracle Net Assistant^[1], a tool used for network configuration in earlier Oracle releases, was officially sunset after Oracle9i. In Oracle Database 10g and later, the functionality of Oracle Net Assistant was replaced by Oracle Net Manager and Oracle Net Configuration Assistant (NetCA), which continue to provide network configuration tasks like managing listeners, configuring service names, and other network-related tasks. The transition from Oracle Net Assistant to Oracle Net Manager occurred with Oracle Database 10g, and Oracle Net Assistant was last available in Oracle 9i.
Oracle Net Manager from Oracle 11g Release 2 has not been explicitly discontinued but has been largely superseded by more modern tools in later Oracle database versions. While Oracle Net Manager is still available and functional in Oracle 11g Release 2, many of its features have been gradually integrated into Oracle's broader network configuration and management tools, such as 1) Oracle Net Configuration Assistant and 2) Oracle Enterprise Manager Cloud Control. These tools provide more comprehensive functionality for configuring network environments in newer releases.
Moreover, certain features related to Oracle Net Services, such as connection pooling, have been deprecated, indicating Oracle’s shift toward evolving technologies for managing network configurations in its newer database versions. However, the core functionality of Oracle Net Manager in 11g Release 2 remains usable for network configuration tasks like listener management and TNS naming. If you're working with more recent Oracle versions, it might be worth exploring updated tools that Oracle provides for network services management.

Oracle officially ended Premier Support for Oracle Database 11g in 2015 and Extended Support in 2020. However, Oracle still offers Sustaining Support, which is an indefinite support tier provided for older Oracle Database versions like 11g. Sustaining Support offers access to Oracle’s technical support and the ability to receive updates for known issues. However, it does not include new updates, fixes, or patches, including critical security updates that are typically covered under Premier and Extended Support. For organizations using Oracle 11g, migrating to a newer, "cloud-enabled version" such as Oracle 19c or 23c is generally recommended. These versions are optimized for cloud environments and offer full support along with the latest security features and improvements. If continuing to use 11g, some enterprises purchase additional custom support agreements from Oracle, but these are generally more expensive and limited in scope. If you’re running cloud databases, Oracle offers support for its "Autonomous Database" and "Oracle Cloud Infrastructure", which can be valuable when upgrading to modern, cloud-enabled database solutions.

Oracle has transitioned to using Oracle Enterprise Manager Cloud Control and Oracle Database Express (EM Express) as the preferred tools for database management and listener configuration. Oracle Enterprise Manager Database Control was deprecated and is no longer included or supported in these later releases. While the listener functionality itself remains, the way it is managed has shifted away from Database Control to newer tools.
For Oracle 12c and newer versions, managing listeners is typically done via

1. Oracle Net Manager,
2. Oracle Net Configuration Assistant (NetCA), or
3. EM Cloud Control.

Additionally, many tasks related to listener configuration can also be done using command-line tools like `lsnrctl`.

Oracle Net Manager^[2] was a key tool for configuring network connections in older Oracle databases like 11g. However, with the shift towards cloud-enabled databases, the way we manage network connectivity has evolved. Cloud providers like Oracle Cloud Infrastructure (OCI) offer built-in networking features and services that simplify connectivity. These features often include:

• Virtual Cloud Networks (VCNs): These provide isolated network environments within the cloud where you can launch your databases and other resources.
• Security Lists and Network Security Groups: These act as virtual firewalls, controlling inbound and outbound traffic to your database instances.
• Load Balancers: These distribute traffic across multiple database instances for high availability and scalability.
• Service Gateways: These provide private connections between your VCN and other Oracle services, enhancing security.

Instead of directly configuring listeners and connect descriptors like you would with Oracle Net Manager, you typically use these cloud-native networking services to manage connectivity. This allows for greater automation, scalability, and security in cloud environments. So, while Oracle Net Manager was essential for on-premises 11g databases, cloud-enabled databases leverage the cloud provider's networking capabilities for a more streamlined and efficient approach.

[1] Oracle Net Assistant: Oracle Net Assistant, a graphical tool used for basic network configuration in older Oracle database versions, was eventually replaced by the more robust Oracle Net Manager. Oracle Net Manager offered a wider range of configuration options and a more user-friendly interface. However, both tools have been deprecated in favor of command-line utilities and newer graphical tools like Oracle Enterprise Manager (OEM) which provide more comprehensive network management capabilities for modern Oracle databases.

[2] Oracle Net Manager: Oracle Net Manager was a graphical tool used to configure network communication for Oracle databases before the widespread adoption of cloud databases. It allowed administrators to easily manage network components like listeners, naming methods, and connect descriptors, which were essential for clients to connect to the database server. Essentially, it simplified the process of establishing and managing network connections for Oracle databases in a pre-cloud environment.