1Q: We are testing a Cisco N540-24Q8L2DD-SYS with 3rd party QSFP-100G-ZR4-S modules. Apparently, the Cisco IOS XR doesn‘t support a QSFP-100G-ZR4-S yet, so these are coded as QSFP-100G-ELR4 to be recognized by the Cisco IOS. They appear to work fine at 80KM. Are your QSFP-100G-ZR4-S modules coded thise way?
A: Our QSFP-100G-ZR4-S uses 100G ER4 codes and the part number will be identified 100G ER4, but the module can work on the device normally.
2Q:If a 100G link is 120km away, would I need to install an EDFA for the link?
A:Yes, you‘ll need to install an EDFA.

3Q: What if this module can guarantee 0.25 dB/km of loss when transmitting at 80km?
A:The maximum transmission distance for this module is 80km. Therefore, theoretically, 0.25 dB/km of loss is guaranteed.
4Q: My device is Cisco N540-28Z4C-Sys, please help to verify if HTQS-HS4CZ is compatible.
A: I bought this one before. This QSFP28-ZR4-100G module is fully compatible with my N540-28Z4C-Sys switch, and we are using it which still work well.
5Q: My device is HW CE6860, I‘m looking for a 100G 1310nm 80km LC single-mode module, please help to verify if QSFP28-ZR4-100G is compatible.
A:Sure, we have tested the  HTQS-HS4CZ module on the HW CE6860 switch, it can be connected and used normally, and the DOM information is displayed normally.
6Q: Will this work with my Cisco Nexus 93180YC switch?
A: Yes, I have Nexus 93180YC, and tested well.