To explicitly answer the question…
The default timeout is infinite.
By default RestTemplate uses SimpleClientHttpRequestFactory and that in turn uses HttpURLConnection.
By default the timeout for HttpURLConnection is 0 – ie infinite, unless it has been set by these properties :
-Dsun.net.client.defaultConnectTimeout=TimeoutInMiliSec
-Dsun.net.client.defaultReadTimeout=TimeoutInMiliSec