What Is Network Detectionand Response (NDR)?
Network Detection and Response (NDR) analyzes network traffic to find suspicious activity and give investigators evidence they can follow. It can show which systems communicated, how activity moved inside the network, and what happened before and after a detection.
How NDR works.
NDR needs visibility into the traffic you care about. That can include north-south traffic entering or leaving the environment and east-west traffic moving between internal systems.
Collect the traffic
Network evidence can come from taps, SPAN ports, packet brokers, flow records, cloud network telemetry, or imported captures.
Turn it into usable evidence
Connections become records: source and destination, ports, protocols, timing, DNS activity, session details, data volume, and payload content when available.
Look for suspicious patterns
Rules, threat intelligence, behavioral analysis, baselines, and correlation can surface activity that deserves investigation.
Give the analyst a trail
The useful output is the evidence around the activity: systems involved, sessions, sequence, timing, and enough context to investigate what happened next.
The exact collection method and response capability vary by product. NDR cannot analyze traffic it never receives.
What does NDR actually look at?
There is no single NDR data format. The depth of the investigation depends on what the platform can collect and retain.
Packets and PCAP
Full packet data can preserve protocol headers and, when visible, payload content for deeper forensic review.
Flow and session records
NetFlow, sFlow, and similar records show who communicated, over which ports and protocols, when, and how much data moved.
Protocol metadata
Zeek and similar telemetry can turn DNS, HTTP, TLS, SMB, SSH, and other network activity into searchable records.
Network security events
Firewall, IDS/IPS, proxy, and other network controls can add detections and context around the traffic being investigated.
Cloud network telemetry
Virtual network flow logs and mirrored traffic can extend visibility into cloud workloads where physical taps do not exist.
What kinds of activity can network evidence surface?
NDR is strongest when suspicious behavior leaves a pattern in network communications. These are common examples an analyst may be able to see or investigate.
Lateral movement
A host begins reaching internal systems or services it does not normally use, including new SMB, RDP, SSH, or administrative paths.
Command and control
Repeated outbound connections, unusual destinations, beacon-like timing, or other communication patterns can point to C2 activity.
Reconnaissance and scanning
Bursts of connections across many hosts, ports, or services can reveal internal discovery and network-service scanning.
DNS and protocol abuse
Long or unusual DNS queries, unexpected protocols, uncommon ports, or protocol behavior that breaks the normal pattern can warrant investigation.
Possible data exfiltration
Large or unusual outbound transfers, new destinations, and unexpected transfer methods can provide evidence of data leaving the environment.
Unexpected access paths
New third-party connections, remote access from unusual networks, or communication across a boundary that should be quiet can expose a path worth checking.
Network evidence can show the communication. Host, identity, cloud, or application evidence may still be needed to explain which process or account caused it.
NDR is only as useful as the visibility behind it.
Before judging any NDR platform, check the collection and investigation path first.
Which network segments and sites can the platform actually see?
Can it see internal east-west traffic, internet-facing north-south traffic, or both?
What is retained: full packets, flows, protocol logs, detections, or only summaries?
How much useful context remains when traffic is encrypted?
Can an analyst move from a detection back to the sessions and evidence that support it?
Who owns the investigation and which response actions require human approval?
Where CrunchAtlas fits.
CrunchAtlas can ingest passive network evidence from CrunchSense, existing security tools, PCAP, NetFlow, and Zeek. Suspicious activity can then be investigated with the supporting evidence attached. Network monitoring stays passive, and consequential production changes remain under operator control.
Network Detection and Response
Use passive network evidence to see suspicious communication and movement across supported IT and OT segments, then carry the finding into an investigated case.
Explore NDR → 02Alert Investigation
Work detections against supporting and conflicting evidence, establish the scope the evidence supports, and deliver a verdict and next step for review.
Explore Alert Investigation →The same case can continue into forensics, campaign correlation, and incident reporting without starting the investigation over.
NDR questions, answered.
What does NDR stand for?
NDR stands for Network Detection and Response. It refers to security technology that analyzes network traffic or network telemetry to detect suspicious activity and support investigation and response.
How is NDR different from IDS or IPS?
IDS and IPS focus on detecting suspicious network activity, with IPS also able to block traffic inline. Modern NDR usually adds broader traffic analytics, historical context, investigation workflows, and response capabilities. The exact boundary varies by product.
Does NDR replace EDR?
No. NDR sees network communications. EDR sees activity on the endpoint, such as processes, files, registry changes, and host behavior. The two evidence sources often answer different parts of the same investigation.
Can NDR still help when traffic is encrypted?
Yes, but with limits. Even without payload visibility, metadata such as endpoints, ports, DNS activity, TLS characteristics, timing, session duration, and data volume may still support detection and investigation. What is visible depends on the collection method and product.
Can NDR monitor OT networks?
Yes, when the deployment can safely observe the relevant OT segments and protocols. Passive collection is often useful because it can monitor communication without actively probing operational devices. Coverage still depends on placement, telemetry, protocol support, and operating constraints.
Primary guidance
The network-traffic, detection, and OT concepts on this page are grounded in MITRE ATT&CK, CISA, and NIST guidance. CrunchAtlas product descriptions are separate from agency guidance.
This page is educational. NDR coverage and conclusions depend on network architecture, collection points, telemetry, retention, encryption, integrations, and approved scope.
See what your network evidence can tell you.
Bring the traffic or telemetry you already have. See how CrunchAtlas carries suspicious network activity into an investigated case.
Visibility and conclusions depend on available telemetry and approved scope. Operators retain control of consequential actions.