One of the challenges in developing a SLA for network services is finding performance metrics that can be measured properly and reflect the quality of service expected by the customer. Establishing a well-designed framework for network services is not a challenge, but a good practice. Ensuring that network components are not modified by the client or reducing the number of entry points into the network are security issues, not SLA issues. References: ISACA, CISA Review Manual, 27th Edition, 2018, page 333