Netconf is a protocol proposed by the IETF that defines a set of operations for network configuration. One of the main issues of Netconf is to define operations such as validate and commit, which currently lack a clear description and an information model. We propose in this paper a model for validation based on XML schema trees. By using an existing logical formalism called TQL, we express important dependencies between parameters that appear in those information models, and automatically check these dependencies on sample XML trees in reasonable time. We illustrate our claim by showing different rules and an example of validation on a Virtual Private Network.