Cisco Certified Network Professional 2025 – 400 Free Practice Questions to Pass the Exam

The default Maximum Transmission Unit (MTU) size for Ethernet is 1500 bytes. This value is standardized for Ethernet networks and represents the largest packet size that can be transmitted over the network without fragmentation.

In practice, the 1500-byte MTU size is widely used for standard Ethernet frames, ensuring compatibility and efficient data transfer across diverse networking equipment and configurations. An MTU size of 1500 bytes allows for an optimal balance between transmission efficiency and resource use, as it minimizes the overhead caused by packet fragmentation while maintaining the ability to carry typical network traffic.

Other MTU sizes, such as 1200 bytes, 9000 bytes (which refers to Jumbo Frames, used in specific contexts for large data transfers), and 1600 bytes, may be applicable in various networking scenarios but are not the default setting for standard Ethernet. The default of 1500 bytes has become entrenched in Ethernet standards and is recognized across a wide array of network devices, making it a critical concept for network configuration and management.