High-availability Seamless Redundancy (HSR)

Data Center
Data Communication Equipment
Data Terminal Equipment (DTE)
D Channel (Delta Channel)
Destination Point Code (DPC)
Diameter Edge Agent
Diameter (Protocol)
Diameter Routing Agent
Differentiated Services Code Point (DSCP)
Digital Cross-Connect System (DCS)
Digital Loop Carrier (DLC)
Direct Inward Dialing/Direct Outward Dialing (DID/DOD)
Disk Operating System (DOS)
Distributed Denial of Service (DDoS)
Domain Name System (DNS)
Dual Homing
Dual Tone Multi-Frequency (DTMF)
Dynamic Host Configuration Protocol (DHCP)