so, what is the best way to judge the chain. In fact, we can completely reverse thinking.
third snapshot. The snapshot actually reflects the update frequency, if it is a commercial station or navigation station, the page is not always updated snapshot, certainly not, but it can never say it weight low.
second, the number of the chain changes too much, especially some of the chain group, can make a website with tens of thousands of spam links in a short period of time, not a few days will drop down, ask the rubbish the chain with the number of what, what reference value.