Network monitoring tools explained: Concepts and utilities for IT teams

PING

The primary PING utility use the ICMP (Internet control message protocol) to send data packets. Each ICMP packet contains a header and a payload. In Windows devices, 32 bytes of data is sent with the payload. In MacOS devices, 56 bytes of data is sent. Once the destination device receives the data, it sends back the same amount of data as a reply.

What can you monitor with a PING tool?

• Uptime status
• Round-trip time
• DNS name/IP address
• Packet loss

Why is PING important?

ICMP is a fundamental network protocol that sits directly on top of the Internet Protocol (IP): This ensures compatibility with any network device or system. ICMP echoes are also lightweight, adding very little overhead to your network. A single PING test helps you measure both the reachability and speed of a network connection.

This simplicity and reliability have contributed to the widespread adoption of the PING utility. It is built into every modern operating system with a network stack, including Windows, macOS, Linux, Unix, BSD, Android, and iOS. Many modern network monitoring tools also use PING to track the uptime of key IT components.

SNMP PING

SNMP PINGs use the standard network management protocol (SNMP) to monitor network devices. Unlike normal PINGs, SNMP PING uses a GET request to obtain information from the recipient device. Instead of getting an identical message as a reply, the recipient device sends an answer to the query asked by the sender.

SNMP communications are enabled by a device's software layer. Information about the device is stored in a text-database called the Management information base (MIB). Each data item in an MIB is stored with a unique ID, known as an object identifier (OID). SNMP PING uses OIDs to gather more information than a normal PING test. Most SNMP PING tools query the name and description of a device stored within its MIB.

Why is SNMP PING important?

While normal PING checks whether the device is plugged in and running. SNMP PING goes one step further and verifies whether the management interface is working. Moreover, some organizational firewalls are configured to block ICMP requests, SNMP PING is a useful alternative in such networks.

Proxy PING

Proxy PING (Otherwise known as remote PING, distributed management PING, or SNMP-triggered PING) checks the availability of a network component through a separate or "proxy" router. Proxy PING is performed by a central console which sends an SNMP SET request to the router. The router then sends an ICMP PING to the recipient device. Once the router gets a response from the recipient device, the console uses an SNMP PULL request to fetch the uptime status of the recipient device.

Why is Proxy PING important?

Proxy PING is useful in troubleshooting network issues in distributed infrastructure.

• If a branch office loses connection to a service, running a proxy ping from that branch's router helps find out whether it's a local issue or an ISP issue.
• If the monitoring console is blocked from accessing a device due to security reasons, proxy PING is a good alternative.
• You can check the connectivity of a device through multiple network segments.

Traceroute

Traceroute is a diagnostic utility used to track the path that data packets take from a source device to a destination device. It maps the route hop-by-hop across routers and switches, showing the delay (latency) at each point along the way.

Traceroute operates by manipulating the TTL field in the IP header of the packets it sends. The TTL acts as a self-destruct counter that prevents packets from looping endlessly. The first packet is sent with a TTL of 1. The first router it hits reduces the TTL to 0, discards the packet, and sends back an ICMP "Time Exceeded" message. this router's IP and response time are recorded. It then adds the TTL to 2, 3, 4, and so on, finding each router along the path until the packet reaches its destination.

What can you monitor with a Traceroute tool?

• The list of routers in a network path
• The round-trip time (RTT) to each intermediate router (Usually measured three times per hop to identify fluctuations)
• Points in the network where transit delays occur
• The exact router where data packets were dropped

Why is Traceroute important?

While a simple PING tells you if a connection is down, Traceroute tells you where it is failing. If a service becomes unreachable, running a Traceroute helps you determine if the outage is inside your local network, within your Internet Service Provider's (ISP) infrastructure, or at the destination server itself.

Additionally, Traceroute is built into almost all modern operating systems making it universally accessible for rapid network troubleshooting.

MAC Address Resolver

Media Access Control (MAC) addresses are physical hardware addresses used within local area networks (LANs) to move data between devices connected to the same physical network segment (the data link layer). Devices in the LAN translate network-layer IPs to the data link-layer MAC addresses during data transit. A MAC address resolver is used to do the same thing: to find the MAC address associated with a specific IP address on a LAN.

Why is a MAC address resolver important?

IP addresses can change frequently due to DHCP leasing, but MAC addresses are physically burned into the network card at the factory. This makes MAC address resolution critical for device tracking, inventory management, and security.

If a rogue device joins your network, a MAC address resolver can help security administrators identify the physical manufacturer of the machine and block it at the switch level. It is also essential when configuring DHCP reservations, ensuring that specific physical devices always receive the same IP address.

DNS Resolver

A DNS resolver (Domain Name System resolver) is a tool or service that transforms human-readable domain names (like google.com) into the machine-readable IP addresses (like 8.8.8.8).

A DNS resolver acts as the middleman between your computer and the global DNS database. When you type a website name into your browser, the resolver starts a search query. It checks the local cache first. If the address isn't saved there, it queries a chain of DNS servers—starting with Root servers, moving to Top-Level Domain (TLD) servers (like .com or .org), and finally reaching the Authoritative Name Server that holds the actual IP map. Once found, the resolver delivers the IP back to your device and saves it in its cache for future use.

Why is a DNS resolver important?

Network administrators monitor DNS resolvers to diagnose configuration errors, detect DNS hijacking (where users are redirected to malicious sites), and ensure that newly updated domain records are propagating correctly.

DHCP Scope Monitor

A DHCP scope monitor is an administrative tool used to track and manage the IP addresses allocated by a Dynamic Host Configuration Protocol (DHCP) server.

A scope is the consecutive range of IP addresses that a DHCP server is authorized to lease out to devices on a given subnet.

The DHCP scope monitor constantly queries the DHCP server to keep track of how many IPs are currently leased out to active devices, how many remain available in the pool, and which reservations or exclusions are active.

Why is a DHCP scope monitor important?

If a DHCP scope runs out of IP addresses (IP exhaustion), new devices—like an employee's laptop or a customer's phone—will not be able to join the network at all. They will get stuck with a self-assigned IP address and lose all network connectivity.

A DHCP scope monitor helps network administrators avoid this issue by sending alerts when a scope's usage reaches critical thresholds (e.g., 85% capacity). This allows admins to proactively expand the IP range, shorten lease times, or clean up dead leases before network access is disrupted.

SNMP Tools

SNMP tools are widely used to monitor the physical health of network devices, servers, and infrastructure components. Unlike operating system-specific tools, SNMP provides a vendor-neutral standard that allows monitoring applications to query hardware health statistics from routers, switches, storage arrays, and servers regardless of the manufacturer.

Why are SNMP tools important?

SNMP is supported by virtually every enterprise hardware manufacturer right out of the box, making it the bedrock of infrastructure monitoring. It allows administrators to oversee a heterogeneous data center containing equipment from dozens of different vendors through a single, centralized dashboard.

CLI tools

Command-Line Interface (CLI) tools are utilities used by administrators to monitor network components directly via text-based commands and network protocols. These tools establish a direct connection to a device's OS.

CLI hardware monitoring relies on various network protocols depending on the recipient device. For Windows servers, admins use Windows Management Instrumentation (WMI) or its modern successor, CIM (Common Information Model), often executed via PowerShell.

For Linux, Unix, and network hardware (like switches and routers), secure cryptographic network protocols like SSH (Secure Shell) are used to log in remotely and run native hardware diagnostic commands. In rare, legacy scenarios within isolated networks, Telnet might be used, though it has been widely phased out due to lack of encryption.

Why are CLI tools important?

CLI commands can be easily automated using shell scripts or integrated into configuration management platforms. This allows administrators to schedule routine hardware checks, parse the text output automatically, and trigger alerts if a metric violates safe operational thresholds.

IPMI tools

Intelligent Platform Management Interface (IPMI) tools are specialized utilities used to manage and monitor server hardware independently of the operating system. IPMI operates via a dedicated hardware sub-system known as a Baseboard Management Controller (BMC): a specialized controller embedded directly onto the motherboard.

Because the BMC runs on standby power as long as the server is plugged in: The tool can query hardware sensors and control the server even if the primary operating system is completely frozen, crashing, or turned off.

Why are IPMI tools important?

IPMI tools are the ultimate fallback for data center reliability. If a remote server suffers a catastrophic operating system crash (such as a kernel panic or Blue Screen of Death), traditional CLI tools like SSH or WMI become completely unresponsive.

With an IPMI tool, an administrator can remotely log into the BMC, read the hardware event log to diagnose if a physical component failed, and issue a hard hardware reset or power cycle to bring the server back online.

NetFlow/jflow/Netstream/IPFIX

NetFlow is a protocol developed by Cisco that collects and exports information about IP traffic as it passes through a router or switch. Rather than tracking every packet individually, NetFlow groups packets into flows. A flow is defined by a shared set of attributes: typically the source and destination IP address, source and destination port, and protocol type. This is often called the five-tuple.

Other vendors built their own versions of the same idea. Juniper's implementation is called jFlow, and Huawei's is called NetStream. To reduce this vendor fragmentation, the IETF standardized IPFIX (IP Flow Information Export), a vendor-neutral protocol based on NetFlow version 9's flexible, template-based format.

What can you monitor with NetFlow?

• Top talkers on the network
• Bandwidth usage by application or protocol
• Traffic patterns between specific source and destination pairs
• Unusual spikes that may signal a security incident

Why is NetFlow important?

NetFlow gives administrators visibility into who is actually using the network and for what purpose. PING and Traceroute can't offer that on their own. If a link suddenly becomes saturated, NetFlow can quickly show which application, device, or user is responsible. Because flow records are lightweight summaries rather than full packet copies, NetFlow can run across large networks without placing a heavy processing load on routers and switches.

sFlow

sFlow (short for sampled flow) is an industry-standard technology, developed by InMon Corporation, used to monitor traffic on switched and routed networks through statistical sampling rather than full flow tracking.

Unlike NetFlow, sFlow doesn't build or maintain flow records on the device itself. Instead, it randomly samples a small fraction of packets. For example, 1 out of every 1,000, and forwards a truncated copy of each one to a central collector. It also polls interface counters at set intervals and sends that data along too. The collector, not the device, does the work of reconstructing flow information from these samples.

Why is sFlow important?

sFlow places very little strain on router and switch hardware, even on extremely high-throughput links. This makes it well suited to large data centers and service provider networks, where full flow-state tracking could overwhelm device resources. Many switch vendors build sFlow support directly into hardware, which has made it a popular choice for organizations running mixed-vendor networks.

AppFlow

AppFlow is a flow-export technology, built on the IPFIX standard, that captures data at the application layer instead of just the network layer. It was developed by Citrix for use with its application delivery controllers, which sit in front of web applications and manage traffic between clients and servers.

While standard IPFIX and NetFlow records typically capture only the five-tuple, AppFlow adds Layer 7 details such as HTTP URLs, response codes, and transaction times. This gives administrators insight into how an application is actually performing, not just how much traffic it's generating.

Why is AppFlow important?

Traditional flow tools can show that traffic to a web server has spiked, but they can't explain why users are experiencing slow load times. AppFlow closes that gap by exposing application-specific performance data. This helps teams pinpoint whether a slowdown comes from the network, the server, or the application itself. Because it's built on IPFIX, AppFlow data can often feed into the same collectors already used for standard flow analysis.

gNMI

gNMI (gRPC Network Management Interface) is a protocol built as part of the OpenConfig project. OpenConfig is an effort led by large network operators to create vendor-neutral standards for configuring and monitoring network devices. gNMI runs over gRPC, a high-performance remote procedure call framework built on HTTP/2, and uses Protocol Buffers to encode data compactly.

Unlike older tools that separate configuration from monitoring, gNMI combines both in a single interface. Its core operations let a client retrieve device state (Get), push configuration changes (Set), and, most relevant to telemetry, subscribe to a continuous stream of updates (Subscribe). Once a client subscribes to a data path, the device pushes new values the moment they change, rather than waiting to be asked.

What can you monitor with gNMI?

• Interface status and utilization
• Routing table changes
• CPU, memory, and temperature metrics

Why is gNMI important?

Because updates are pushed instantly instead of pulled on a schedule, gNMI lets administrators catch problems like interface flaps or routing changes within milliseconds, instead of the minutes it can take with SNMP polling. Its unified approach to configuration and monitoring also means network teams can manage both through a single, vendor-neutral protocol. This is one reason major router and switch manufacturers have adopted it as a modern alternative to SNMP.

YANG Push

YANG (Yet Another Next Generation) is a data modeling language, standardized by the IETF, used to define the structure of configuration and operational data on network devices. On its own, YANG doesn't move any data. It only describes what that data looks like.

YANG Push puts those models to work for streaming telemetry. It lets a client subscribe to a specific piece of YANG-modeled data and choose how updates should arrive: either periodically, at a fixed interval, or "on-change," where the device sends an update only when the underlying value actually changes. YANG Push typically runs over NETCONF, which handles the delivery of subscribed updates.

Why is YANG Push important?

On-change subscriptions mean a device only sends data when something meaningful happens, cutting down on the constant chatter created by traditional polling. Because YANG models are standardized rather than vendor-specific, YANG Push also delivers consistent, structured data across a multi-vendor network, instead of the inconsistent text output produced by CLI commands. This makes it well suited to automated systems that need to react to network changes the moment they happen.