QSFP-DD (Quad Small Form-Factor Pluggable Double Density) is a high-speed transceiver module that provides double the density of ports compared to traditional QSFP modules. QSFP-DD is designed to support various data rates depending on the specific variant.

1. 200 Gigabit Ethernet (200GbE): QSFP-DD modules can support a data rate of 200 Gbps, allowing for high-speed network connections.

2. 400 Gigabit Ethernet (400GbE): QSFP-DD is particularly significant in its support for 400 Gbps data rates, making it a crucial component for high-performance data center networks.

The QSFP-DD form factor provides a larger number of electrical lanes and optical channels, allowing for increased data throughput compared to earlier QSFP modules. It's important to note that specific implementations of QSFP-DD modules may vary, and new developments in networking technology could introduce higher data rates in the future.

For the most up-to-date information on QSFP-DD and its supported data rates, it's recommended to refer to the latest specifications provided by standards organizations such as the QSFP-DD MSA (Multi-Source Agreement) or the relevant industry standards bodies.