The primary network card is typically the default network interface that a computer uses to connect to the internet or a local network. It is usually assigned the default gateway and DNS server settings, making it the primary means of network communication. For example, when you connect your computer to a Wi-Fi network, the Wi-Fi adapter often becomes the primary network card.
On the other hand, a secondary network card is an additional network interface that can be used for various purposes, such as connecting to a different network, setting up a VPN, or enabling network redundancy. It can be a physical card installed in a PCIe slot or a virtual network interface. For instance, a server might have a primary network card for internet access and a secondary network card for internal communication within a data center.
In the context of cloud computing, Tencent Cloud offers services like Elastic Network Interface (ENI), which allows you to create and manage multiple network interfaces for your instances, providing flexibility for different networking needs.