GCIA: GIAC Certified Intrusion AnalystDemo

John is a professional Ethical Hacker. He has been assigned a project to test the security of www.we-are-secure.com. He scans the We-are-secure server and obtains the following result:

sysDescr.0 = STRING. "SunOS we-are-secure.com 4.1.3_U1 1 sun4m"  
sysObjectID.0 = OID. enterprises.hp.nm.hpsystem.10.1.1  
sysUpTime.0 = Timeticks: (156474552) 18 days, 12:00:09  
sysContact.0 = STRING. ""  
sysName.0 = STRING. "we-are-secure.com"  
sysLocation.0 = STRING. ""  
sysServices.0 = INTEGER: 6  

Which of the following tools is John using to perform the scan?