What does SD-WAN stand for?
SD-WAN stands for Software-defined Wide Area Network. Centrally managed software that connects branch sites over whatever links are available, such as broadband, LTE and MPLS, steering each application over the best path by policy. It cuts the cost of dedicated circuits and gives one console for all sites.
SD-WAN applies the software-defined idea to the links between sites. Each site has an edge device connected to two or more transports, for example an MPLS circuit, a broadband line and a cellular link. The devices build encrypted tunnels over all of them, measure loss, delay and jitter continuously, and steer each application onto the link that suits it at that moment. Policies are written once on a central controller and pushed to every site. The practical gains are cheaper bandwidth, automatic failover and new sites that configure themselves when they are plugged in.
SD-WAN in practice: an example
A chain of clinics has an MPLS line and a cheaper broadband line at each site. The policy says that video consultations use whichever link has the lowest loss right now and that backups use broadband only. One afternoon the MPLS line at a clinic degrades. Calls move to broadband within seconds and staff notice nothing, while the controller shows the event for the whole chain on one screen.
What SD-WAN is confused with
SD-WAN vs MPLS: what is the difference?
MPLS is a carrier service: a private, predictable path sold site by site. SD-WAN is an overlay run by the customer, which can use MPLS as one of its links next to ordinary internet lines.
SD-WAN vs SDN: what is the difference?
SDN separates control from forwarding inside a network, typically a data centre. SD-WAN brings the same central-controller idea to the wide-area links between sites. What SDN stands for
SD-WAN vs SASE: what is the difference?
SASE combines SD-WAN with cloud-delivered security services. SD-WAN on its own is the networking part. What SASE stands for
Which exams cover SD-WAN?
SD-WAN is on the official CompTIA acronym list for one of the four exams covered here.
- Network+ N10-009: 1.0 (Networking Concepts).
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. A company wants each branch to use both an MPLS circuit and an internet line, with applications moved automatically to the better link and policy managed centrally. Which technology provides this?
- SD-WAN
- Spanning Tree Protocol
- Port address translation
- Power over Ethernet
Show the answer
A. SD-WAN. Application-aware path selection across several WAN links under a central controller is what SD-WAN does.
2. What does an SD-WAN edge device measure in order to choose a link for voice traffic?
- Loss, latency and jitter on each link
- The size of the MAC address table
- The DHCP lease time
- The number of VLANs
Show the answer
A. Loss, latency and jitter on each link. Path selection is based on live measurements of link quality. Voice is sensitive to all three, so the edge sends it over the link where they are lowest.
Sources: MEF 70.1: SD-WAN Service Attributes and Service Framework; Microsoft Learn: SD-WAN connectivity architecture with Azure Virtual WAN. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 12 November 2026.