# Challenge Coordination

In order to vet the quality and coverage of capacity provided by participating CDNs, nodes prove their resources by participating in distributed challenges of their backhaul, multicast coverage, uptime, and location. Challengers can be nodes on the Blockcast network or other DePINs by leveraging Witness Chain’s DePIN coordination layer.

<img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXe065bD-H6NWY6accHwABsarvuKYE_8hFkOryAbcvCzFrJIJNayZ8-KIVKkzzmvgdwO_ckxyiXegxjhRndIRGwVEXcj_PTdqnKip7wMq3RaUk139rGElL4rKl7F04W5iv2tOH_P8Oi7euggK361L4_QxrRg?key=rUAtSF88doEQot6P43JZKQ" alt="" data-size="original">


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