I. What is an Elastic Network Interface (ENI)?
- An ENI is a virtual network API. Users can bind with a CVM to an ENI to connect with the network. ENIs are very helpful in configuring and managing networks and building highly reliable network solutions.
- An ENI combines VPC, availability zone, and subnet attributes and can only be bound to CVMs in the same availability zone. A CVM can be bound to multiple ENIs, and the specific number of bindings will depend on the host specifications.
II. What is the difference between the primary network interface and the secondary network interface?
- The primary network interface is assigned to the user by the system and the information cannot be modified.
- The secondary network interface is created by the user and the information can be modified.
III. What are the restrictions on using ENIs?
Depending on the CPU and memory configuration, the number of ENIs that can be bound to a CVM and the number of private IPs that can be bound to a single network interface can vary greatly. For details, see the Usage Restrictions section.
IV. What should I do if the elastic IP is not accessible?
If the Elastic IP (EIP) is not accessible, consider the following reasons:
- EIP addresses are not bound to cloud services.
- The security policy is invalid. Users can check whether the security policy (security group or network ACL) is effective.
- Disable port access. Even if the bound cloud services instance has a security policy, if the port is prohibited from access, the port of the EIP is also inaccessible. For example, if access to port 8080 is prohibited, port 8080 of the EIP will also be inaccessible.