PBNs are currently considered a pure black hat strategy and is recommended to avoid completely in any case as they can result in low rankings or even pave way for a manual penalty. PBNs more often provide only little to no long-term value to the sites they are connecting to. Google has been battling PBNs for quite a long time. As Google improves its innovations to battle link spam techniques, it has turned out to be increasingly hard for black hat SEOs to pull off a PBN effectively.
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