What are the default values of nodes and internal layers in Neural Network models?
There are websites that explain these pretty well. 

Deciding on the number of neurons in the hidden layer(s)

From https://www.r-bloggers.com/selecting-the-number-of-neurons-in-the-hidden-layer-of-a-neural-network/:


  The most common rule of thumb is to choose a number of hidden neurons between 1 and the number of input variables.


Deciding on the number of layers of hidden layers

From https://stats.stackexchange.com/questions/181/how-to-choose-the-number-of-hidden-layers-and-nodes-in-a-feedforward-neural-netw:


  For most problems, one could probably get decent performance (even without a second optimization step) by setting the hidden layer configuration using just two rules: (i) number of hidden layers equals one; and (ii) the number of neurons in that layer is the mean of the neurons in the input and output layers.


Hope that answers your question!