4x4 fence bracing

[AKyardbirds]

What is the proper way to connect a 4x4 to brace another 4x4? I am building N braces for a pen and need advice. In pic 2 you can see there is no lag bolt or screws coming from the back side. These pics are from the same farm so they most likely used the same method in both pics.

 

[tracecom]

Most likely, the diagonal pieces are "toe-nailed" to the horizontal and vertical members, using 16 penny coated nails. You should be able to see the nail heads. The builder might also have used screws. Neither way is a good long term solution. Face nailing 2 x 4 cleats to the horizontal and vertical members. and cutting a matching surface on the ends of the diagonals would work, but it's a lot of trouble. Even better is to notch the horizontal and vertical member, and recess the ends of the diagonals in the notches.