user196: How can I know which testnet am I on?
I just ran bitcoind -testnet, and I would assume it would connect to the most recent one, but is there a way to know it?

user5757: To double check, the genesis block for testnet3 (the current version as of this writing) has hash 000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943.  So with the daemon running, you can do
 bitcoind -testnet getblock 000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943
If you are really on testnet3, you should see "height: 0" in the output.

user208: 
Bitcoin and bitcoind versions v0.3.14 - v0.3.19 used the first testnet.
Bitcoin, Bitcoin-Qt and bitcoind versions v0.3.20 - v0.6.1 used the second testnet.
Bitcoin-Qt and bitcoind version v0.7.0 and above use the third testnet.


196: <p>How can I know which testnet am I on?</p>

<p>I just ran <code>bitcoind -testnet</code>, and I would assume it would connect to the most recent one, but is there a way to <em>know</em> it?</p>
 5757: <p>To double check, the genesis block for testnet3 (the current version as of this writing) has hash <code>000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943</code>.  So with the daemon running, you can do</p>

<pre> bitcoind -testnet getblock 000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943</pre>

<p>If you are really on testnet3, you should see "height: 0" in the output.</p>
 208: <ul>
<li>Bitcoin and bitcoind versions v0.3.14 - v0.3.19 used the first testnet.</li>
<li>Bitcoin, Bitcoin-Qt and bitcoind versions v0.3.20 - v0.6.1 used the second testnet.</li>
<li>Bitcoin-Qt and bitcoind version v0.7.0 and above use the third testnet.</li>
</ul>
