With the growth of telecommunication networks driven by resource-intensive applications, the expansion of IoT, the rise of data centers, and the advancements of 5G and future 6G networks, monitoring and maintenance are becoming increasingly important for network operators. In this sense, the Network Digital Twin (NDT) is emerging as a promising technology to mirror a network’s whole operational and management lifecycle to optimize its performance without compromising the real network. In this work, we propose an NDT solution supported by a new data integration methodology and a prototypical architecture for translating information from the network management domain into a knowledge-based interoperable model. Our case study shows how this NDT can be used to reveal the capabilities of real networks in terms of configuration and operational status, providing benefits for network control and management to facilitate the application of closed-loop network automation systems.