Total number of bitcoin nodes

[pblack4]

What is the total number of nodes in the global bitcoin network?

so far I have found only this http://getaddr.bitnodes.io ..but I don't know if it's a reliable source
I thought there were more than 30K nodes earlier this year, but the above website says 8K-9K

Is there any other website with historical info?

[DannyHamilton]

What is the total number of nodes in the global bitcoin network?

Unknown, and impossible to know.

so far I have found only this http://getaddr.bitnodes.io ..but I don't know if it's a reliable source

It specifically states:
"Bitnodes is currently being developed to estimate the size of the Bitcoin network by finding all the reachable nodes in the network"

After searching through their node list, I can confirm that my node is not listed there, so clearly it doesn't know the exact number.  I have no way of knowing how accurate their "estimate" is.

I thought there were more than 30K nodes earlier this year,

You might be right.  How would we know?

but the above website says 8K-9K

They might be right.  How would we know?

Is there any other website with historical info?

blockchain.info might have some historical info about nodes that they have connected to.  I'm not sure if there are any other services providing historical info about nodes they've connected to.

[pblack4]

Thanks.  I'm just wondering what kind of impact the number of nodes may have on the overall network reliability.
The power is currently about 50PH/s but this seems to be spread among 10K nodes only.  Is it correct that to shutdown bitcoin one would have to take 10K nodes down? by physically disconnecting, destroying them or banning their IPs?
Would the network be more reliable if the same power was provided by 100K, 1M+ nodes?