Answer: i think 1, 3, and 4
Explanation:
 
        
             
        
        
        
The protocol that should be used for establishing a secure network connection is SSH.  
The following information is to be considered:  
- SFTP is secure also it is a protocol for file transferring that applied SSH.
- IP, FTP, and DHCP should not be for safety purposes as they are not secure.
- SSH is a secured connection for the remote sites so here the SSH protocol should be used.
Therefore we can conclude that The protocol that should be used for establishing a secure network connection is SSH.
 
        
             
        
        
        
Firewall
Dont forget to thanks and give brianliest.
        
             
        
        
        
Answer:
Incremental method. 
Explanation:
Software development life cycle (SDLC) can be defined as a strategic process or methodology that defines the key steps or stages for creating and implementing high quality software applications.
An incremental model refers to the process in which the requirements or criteria of the software development is divided into many standalone modules until the program is completed.
Hence, an incremental method typically involves developing a system through repeated cycles and smaller portions at a time, enhancing and evolving the system over time.
In SDLC, a waterfall model can be defined as a process which involves sequentially breaking the software development into linear phases. Thus, the development phase takes a downward flow like a waterfall and as such each phase must be completed before starting another without any overlap in the process. 
Also, a spiral model can be defined as an evolutionary SDLC that is risk-driven in nature and typically comprises of both an iterative and a waterfall model. Spiral model of SDLC consist of these phases; planning, risk analysis, engineering and evaluation.