Dell CX4121C Mellanox ConnectX-4 Lx 2 x Ports 25GbE Direct Attach SFP+ Network Adapter Card. In Stock Brand: Dell Part Number: CX4121C Category: Transceiver Key Specs: 25GbE Availability: In Stock Shipping: Fast US-based shipping Order the Dell CX4121C today from ProDisk Network — your trusted source for enterprise IT hardware.
The CX4121C is a Dell transceiver component with network speed 25 GbE. Pricing on the CX4121C is quote-based — email sales@prodisknetwork.com or use our live chat for a quote within one business day.
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Reviewed by:Pro Disk Network Engineering Team — . Specifications, compatibility, and pricing for the CX4121C are shown on this page.
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Same-Day US Shipping — orders before 3pm ET ship today via UPS
30-Day Returns — pre-paid label on DOA and defective items
Quick Answer: Is the CX4121C compatible with my switch?
Pro Disk Network validates every CX4121C against the target switch's published compatibility matrix before shipment. If you let us know your switch model and firmware version, we will confirm fitment and code the module appropriately (Cisco-coded, Juniper-coded, HPE-coded, etc.) at no extra charge.
How fast does the CX4121C ship?
CX4121C orders placed before 3 pm ET ship the same business day from US warehouses. Delivery is next business day to most metro ZIPs via FedEx/UPS overnight; ground delivery covers remaining US in 1-4 business days.
The CX4121C is deployed by US enterprises, MSPs, government, and education customers across multiple infrastructure scenarios. Below are the most common deployment patterns Pro Disk Network sees in real-world orders.
Server Uplink — 10G/25G server-to-leaf uplink — pair with matching DAC or AOC at the host NIC to avoid optic mismatch.
DCI (Data Center Interconnect) — Inter-DC routing or aggregation. LR4/LR8 transceivers for 10–80 km, ER4 for 40 km, ZR4 for coherent long-haul.
Campus Distribution — Catalyst-class campus distribution between IDF and MDF closets. PoE+ where wireless APs and IP phones share infrastructure.
Branch / Edge — Smaller form-factor switches and routers for branch sites. SD-WAN-compatible or static-VPN-attached as the architecture dictates.
What is the CX4121C?
The CX4121C is a Dell network interface module with network speed 25 GbE, manufactured by Dell. Pro Disk Network ships this part new and certified-refurbished from our US warehouse with same-day dispatch on orders placed before 3 PM ET, backed by a 30-day return guarantee.
Pros & Cons of CX4121C
Pros
Same-day US shipping cuts deployment downtime
Cons
Not for hyperscale ZR coherent — different SKU family
Some vendors deprecate firmware on EOL part numbers
Mismatched optic+switch firmware can require manual override
Frequently Asked Questions about CX4121C
Is the CX4121C a genuine Dell part?
Yes. Pro Disk Network sources every CX4121C as factory-original Dell inventory. New units arrive sealed in OEM packaging; refurbished units are pulled from decommissioned Dell servers, surface-tested, and re-warranted by Pro Disk Network for 90 days.
Is the CX4121C compatible with my switch?
Pro Disk Network validates every CX4121C against the target switch's published compatibility matrix before shipment. If you let us know your switch model and firmware version, we will confirm fitment and code the module appropriately (Cisco-coded, Juniper-coded, HPE-coded, etc.) at no extra charge.
How fast does the CX4121C ship?
CX4121C orders placed before 3 pm ET ship the same business day from US warehouses. Delivery is next business day to most metro ZIPs via FedEx/UPS overnight; ground delivery covers remaining US in 1-4 business days.
What is the warranty on the CX4121C?
New CX4121C units carry the full Dell manufacturer warranty (typically 1 to 5 years depending on product line). Refurbished and bulk-OEM units include a Pro Disk Network advance-replacement warranty (90 days refurbished). DOA replacement is free within 30 days of receipt.
Do you offer bulk pricing for the CX4121C?
Email sales@prodisknetwork.com with the quantity and target ship date for a quote within one business day.
Optic Coding, Vendor Lock-In, and Multi-Vendor Compatibility
For Cisco IOS, IOS-XE, and NX-OS switches, the CX4121C works out-of-box if coded for Cisco; for Aruba ArubaOS-CX, code for HPE/Aruba; for Juniper Junos, code for Juniper. Pro Disk Network confirms the target vendor coding at order time and applies it before shipping. Misordered coding can be flashed in the field but the lead time is longer than ordering correctly the first time.
Bandwidth Sizing for Spine-Leaf, EVPN-VXLAN, and Hyperconverged Storage
Document optic types and bandwidth in your network drawings: SR-SR for intra-rack, LR-LR for inter-rack and DCI, ZR4 for long-haul coherent. Mismatched optic-distance ratings is the most common cause of intermittent link errors that look like cable problems but aren't.