Cisco Certified Network Associate (CCNA) Practice Exam

Which command is used to configure a serial port with PPP encapsulation?

1. ip address configuration

2. encapsulation ppp

3. interface serial

4. no shutdown command

The correct answer is: encapsulation ppp

The command to configure a serial port with PPP (Point-to-Point Protocol) encapsulation is encapsulation ppp. This command specifically sets the encapsulation method for the serial interface to PPP, allowing for the establishment of a direct point-to-point link between two network devices. Using this command is essential for ensuring that data packets transmitted over the serial connection are properly formatted and encapsulated according to the PPP standard, which supports features like authentication, compression, and error detection. This configuration is particularly important in environments where reliable and efficient data transport is needed between two endpoints, such as in WAN (Wide Area Network) connections. While configuring a serial interface, other commands such as interface serial are necessary to access the specific interface configuration mode. The ip address configuration command is used to assign an IP address to that interface, and the no shutdown command is important to bring the interface up and make it active. However, none of these commands directly set the encapsulation method, which is why encapsulation ppp is the distinct choice for this particular configuration task.