I would suggest the following books for your preparation towards JNCIE-ENT.
- JNCIP-M Study Guide – for basic knowledge about IGP&Loops, BGP and Policies
- JNCIE-M Study Guide – for QoS and Multicast topics
- Day One: Advanced OSPF in the Enterprise
- Book: Junos Enterprise Routing: A Practical Guide to Junos Routing and Certification (best choice!!!)
- Book: JUNOS Enterprise Switching
I didn’t read any workbook from iNET Zero/Proteus or Twine, so I can’t suggest them. But maybe you have some experience with them and leave comment! Do you know more good sources of informations for JNCIE-ENT?