Network interface card referred to as network card (NIC). It is an indispensable basic device in a computer network that provides physical connectivity for data communication between computers. Each computer must be installed once the network access network card. After many years of development, NIC has become mature. In view of so many types of NIC on the current market, and there are large differences in performance, so it is necessary to classify them in order to better understand the NIC.

Whereas network controllers used to operate on expansion cards that plugged into a computer bus, the low cost and ubiquity of the Ethernet standard means that most new computers have a network interface built into the motherboard. Newer server motherboards may even have dual network interfaces built-in. The Ethernet capabilities are either integrated into the motherboard chipset or implemented via a low-cost dedicated Ethernet chip, connected through the PCI (or the newer PCI Express) bus. A separate network card is not required unless additional interfaces are needed or some other type of network is used.

2 Port Network Card 

The PCI Express Dual Port Gigabit Network Card lets you add two gigabit Ethernet ports to a desktop computer through a single, four-lane (x4 or higher) PCI Express slot. Each port is fully compatible with IEEE 802.3/u/ab standards, for 10/100/1000 Mbps auto-negotiation.

This 2-port GbE network card offers several advanced driver options including IEEE 802.3ad link aggregation / teaming support, enabling you to add additional bandwidth to your system. Support for Jumbo Frames, full-duplex operation and 802.1q VLAN tagging also aid in creating an efficient network configuration.

Difference between having a 2-port Network Card and 2 Network Cards 

Many computers today have the capability of supporting dual network cards. There are several pros and cons to using this type of technology. The primary advantage of two network cards is the ability to simultaneously connect to two completely independent networks. This can increase productivity because one machine can work in two separate environments. The disadvantage is the potential security vulnerabilities that occur through sharing networks on one computer.

Using 2 Network Cards is great idea if you need to connect to 2 different physical networks and in case 1 NIC fails, so you use the other. It can also help with Load balancing &  Separation of traffic (i.e. you could have a combo web/database server, same network, put all web traffic on one NIC, db traffic on the other, makes it easier to calculate loads for traffic types). This also makes it easier to split the two later on, nobody has to change connection strings.

One the other hand using 2 port network card is much more affordable option. If you need more than 1 port, then it's typically cheaper and more space efficient to have more than one port on a NIC. You can purchase NICs with upwards of 4 ports, sometimes higher for NICs with adapters. You can purchase dual port 40Gb NICs that have adapters to allow for 4 10Gb ports per 40Gb port, meaning 8 10Gb ports.

2 port network cards will allow your PC to be connected to two networks at the same time. It also creates aggregation groups that share the same speed and duplex settings and Utilizes all slaves in the active aggregator according to the 802.3ad specification. This mode provides load balancing and fault tolerance but requires a switch that supports IEEE 802.3ad Dynamic Link Aggregation with correct LACP mode configured.
 

What is dual network?

Two electrical networks are said to be dual networks if the mesh equations of one network are equal to the node equation of others. Identical behavior patterns observed between voltages and currents in two circuits illustrate the principle of duality.2

 

What is the use of dual network card?

Dual-network debit cards are debit/ATM cards that allow transactions to be routed through two different networks.

 

Will two network cards speed up?

Your ISP is the one that sets your maximum “internet speed”. The only way multiple cards would work (it has a number of names but generally it's called aggregating) is if the total you receive from your ISP is higher than what your NIC can accept.

 

What are the Pros and Cons of Using Two Network Cards?

Many computers today have the capability of supporting dual network cards. There are several pros and cons to using this type of technology. The primary advantage of two network cards is the ability to simultaneously connect to two completely independent networks. This can increase productivity because one machine can work in two separate environments. The disadvantage is the potential security vulnerabilities that occur through sharing networks on one computer.

A computer with two network cards can connect to multiple computers. Most software developers require access to both a development environment and a separate test environment. Having two network connections enables the developer access to both networks through one computer. Without this feature, the developer is forced to use separate computers for each task.

Most large companies use training software to help employees learn the computer applications that are used by the company. These applications are typically maintained on a separate training network. A computer with two network cards can access both training and production networks. This configuration saves organizations money because the employee can use one computer for both training and production.

Summary

Ethernet ports are force multipliers. With a single computer you can do neat things, but with a network, one plus one is more than two.  When you get to hundreds of computers you get amazing things, and when you have millions of computers you get magic.  The magic wouldn’t happen if every system had just one port, the number of clients would require equal number servers. This is where dual port network card help you.