I am using non-Juniper 10m QFSP+ DAC cables without issue. I am pretty sure they are active.
Hardware inventory:
Item Version Part number Serial number Description
Routing Engine 0 REV 11 650-044931 xxxxxxxxxxxx EX4300-48T
FPC 0 REV 11 650-044931 xxxxxxxxxxxx EX4300-48T
CPU BUILTIN BUILTIN FPC CPU
PIC 0 REV 11 BUILTIN BUILTIN 48x 10/100/1000 Base-T
PIC 1 REV 11 BUILTIN BUILTIN 4x 40GE QSFP+
Xcvr 0 REV 01 740-038624 XAN1710C9290 QSFP+-40G-CU3M
Xcvr 1 REV 01 740-038624 XAN16DCC8583 QSFP+-40G-CU3M
Xcvr 2 REV 01 740-038627 XAN17EB56834 QSFP+-40G-CU10M
Power Supply 0 REV 01 740-046873 1EDE5272206 JPSU-350-AC-AFO-A
Power Supply 1 REV 01 740-046873 1EDE5231445 JPSU-350-AC-AFO-A
Fan Tray 0 Fan Module, Airflow Out (AFO)
Fan Tray 1 Fan Module, Airflow Out (AFO)
FPC 1 REV 03 650-060019 xxxxxxxxxxxx EX4300-24T
CPU BUILTIN BUILTIN FPC CPU
PIC 0 REV 03 BUILTIN BUILTIN 24x 10/100/1000 Base-T
PIC 1 REV 03 BUILTIN BUILTIN 4x 40GE QSFP+
Xcvr 0 REV 01 740-038625 XAN1710D9311 QSFP+-40G-CU5M
Xcvr 1 REV 01 740-038627 XAN17EB56834 QSFP+-40G-CU10M
Power Supply 0 REV 01 740-046876 1EDD5180771 JPSU-350-AC-AFI-A
Power Supply 1 REV 01 740-046876 1EDD4511249 JPSU-350-AC-AFI-A
Fan Tray 0 Fan Module, Airflow In (AFI)
Fan Tray 1 Fan Module, Airflow In (AFI)