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Sudden Traffic Spikes: The Top 5 Causes

Dirk Paessler

When IT departments implement network monitoring tools, they get swarmed with data that they did not have before. This new information gives them the power to act on problems intelligently, oftentimes before they end up affecting end users. The challenge, of course, is to move quickly to identify what issue is causing the problem.

One of the most common problems network monitoring tools are employed to solve are problems with bandwidth. Availability is critical for IT departments of all sizes, and slow bandwidth creates productivity problems and even outages that have a real effect on businesses. Identifying the problems behind bandwidth drains can be difficult, so to help, I’ve put together a list of the five most common causes of sudden traffic spikes.

1. Mail Server Issues

It is not uncommon for a remote mail server to continuously deliver the same email through a company’s servers, even if the target recipient denied acceptance. Incompatibility between the two SMTP implementations creates a sort of endless feedback loop that sees the same email going through the server every five minutes, chewing up bandwidth in the process. The solution involves accessing the target mail server to deny access rights to the remote server.

2. Antivirus

Many of the causes of sudden traffic spikes are security-related, be it malicious traffic, DNS attacks, or sometimes, even the AV itself. Virus scans and software updates distributed inside the LAN are a very common source of traffic spikes, and can be easily dealt with by changing scan settings and performing updates during non-critical business hours.

3. Malicious Traffic

Malware outbreaks and hacking attempts can cause spikes in network traffic, often to either mask other malicious activity or because the malware is attempting to force login to devices.

4. Scheduled Backups

Many backup products are scheduled to run at certain time intervals, or at certain times of day. They also are very network intensive, and if the timing is off, can sop bandwidth during working hours.

5. Remote Backup

Some IT departments opt to use cloud-based tools for backup. While those present certain advantages, one disadvantage is that uploading massive backups to the cloud causes serious load issues. Similar to on-premises backups, these need to be scheduled carefully and performed off-hours.

These are not the only causes of traffic spikes, but it is a good example of common and preventable problems that plague networks. Some problems are more serious and involve hardware failures or router issues, which need to be handled with care and can require spending on new equipment.

In all cases, it is critical for IT departments to establish a baseline for their network traffic so they can understand when it is peaking, and set up appropriate alerts to notify them. Alerting, combined with mapping that identifies where problems are coming from, empowers IT admins to quickly and efficiently troubleshoot most any problem.

Dirk Paessler is CEO and Founder of Paessler AG.

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Sudden Traffic Spikes: The Top 5 Causes

Dirk Paessler

When IT departments implement network monitoring tools, they get swarmed with data that they did not have before. This new information gives them the power to act on problems intelligently, oftentimes before they end up affecting end users. The challenge, of course, is to move quickly to identify what issue is causing the problem.

One of the most common problems network monitoring tools are employed to solve are problems with bandwidth. Availability is critical for IT departments of all sizes, and slow bandwidth creates productivity problems and even outages that have a real effect on businesses. Identifying the problems behind bandwidth drains can be difficult, so to help, I’ve put together a list of the five most common causes of sudden traffic spikes.

1. Mail Server Issues

It is not uncommon for a remote mail server to continuously deliver the same email through a company’s servers, even if the target recipient denied acceptance. Incompatibility between the two SMTP implementations creates a sort of endless feedback loop that sees the same email going through the server every five minutes, chewing up bandwidth in the process. The solution involves accessing the target mail server to deny access rights to the remote server.

2. Antivirus

Many of the causes of sudden traffic spikes are security-related, be it malicious traffic, DNS attacks, or sometimes, even the AV itself. Virus scans and software updates distributed inside the LAN are a very common source of traffic spikes, and can be easily dealt with by changing scan settings and performing updates during non-critical business hours.

3. Malicious Traffic

Malware outbreaks and hacking attempts can cause spikes in network traffic, often to either mask other malicious activity or because the malware is attempting to force login to devices.

4. Scheduled Backups

Many backup products are scheduled to run at certain time intervals, or at certain times of day. They also are very network intensive, and if the timing is off, can sop bandwidth during working hours.

5. Remote Backup

Some IT departments opt to use cloud-based tools for backup. While those present certain advantages, one disadvantage is that uploading massive backups to the cloud causes serious load issues. Similar to on-premises backups, these need to be scheduled carefully and performed off-hours.

These are not the only causes of traffic spikes, but it is a good example of common and preventable problems that plague networks. Some problems are more serious and involve hardware failures or router issues, which need to be handled with care and can require spending on new equipment.

In all cases, it is critical for IT departments to establish a baseline for their network traffic so they can understand when it is peaking, and set up appropriate alerts to notify them. Alerting, combined with mapping that identifies where problems are coming from, empowers IT admins to quickly and efficiently troubleshoot most any problem.

Dirk Paessler is CEO and Founder of Paessler AG.

Hot Topics

The Latest

Enterprises are under pressure to scale AI quickly. Yet despite considerable investment, adoption continues to stall. One of the most overlooked reasons is vendor sprawl ... In reality, no organization deliberately sets out to create sprawling vendor ecosystems. More often, complexity accumulates over time through well-intentioned initiatives, such as enterprise-wide digital transformation efforts, point solutions, or decentralized sourcing strategies ...

Nearly every conversation about AI eventually circles back to compute. GPUs dominate the headlines while cloud platforms compete for workloads and model benchmarks drive investment decisions. But underneath that noise, a quieter infrastructure challenge is taking shape. The real bottleneck in enterprise AI is not processing power, it is the ability to store, manage and retrieve the relentless volumes of data that AI systems generate, consume and multiply ...

The 2026 Observability Survey from Grafana Labs paints a vivid picture of an industry maturing fast, where AI is welcomed with careful conditions, SaaS economics are reshaping spending decisions, complexity remains a defining challenge, and open standards continue to underpin it all ...

The observability industry has an evolving relationship with AI. We're not skeptics, but it's clear that trust in AI must be earned ... In Grafana Labs' annual Observability Survey, 92% said they see real value in AI surfacing anomalies before they cause downtime. Another 91% endorsed AI for forecasting and root cause analysis. So while the demand is there, customers need it to be trustworthy, as the survey also found that the practitioners most enthusiastic about AI are also the most insistent on explainability ...

In the modern enterprise, the conversation around AI has moved past skepticism toward a stage of active adoption. According to our 2026 State of IT Trends Report: The Human Side of Autonomous AI, nearly 90% of IT professionals view AI as a net positive, and this optimism is well-founded. We are seeing agentic AI move beyond simple automation to actively streamlining complex data insights and eliminating the manual toil that has long hindered innovation. However, as we integrate these autonomous agents into our ecosystems, the fundamental DNA of the IT role is evolving ...

AI workloads require an enormous amount of computing power ... What's also becoming abundantly clear is just how quickly AI's computing needs are leading to enterprise systems failure. According to Cockroach Labs' State of AI Infrastructure 2026 report, enterprise systems are much closer to failure than their organizations realize. The report ... suggests AI scale could cause widespread failures in as little as one year — making it a clear risk for business performance and reliability.

The quietest week your engineering team has ever had might also be its best. No alarms going off. No escalations. No frantic Teams or Slack threads at 2 a.m. Everything humming along exactly as it should. And somewhere in a leadership meeting, someone looks at the metrics dashboard, sees a flat line of incidents and says: "Seems like things are pretty calm over there. Do we really need all those people?" ... I've spent many years in engineering, and this pattern keeps repeating ...

The gap is widening between what teams spend on observability tools and the value they receive amid surging data volumes and budget pressures, according to The Breaking Point for Observability Leaders, a report from Imply ...

Seamless shopping is a basic demand of today's boundaryless consumer — one with little patience for friction, limited tolerance for disconnected experiences and minimal hesitation in switching brands. Customers expect intuitive, highly personalized experiences and the ability to move effortlessly across physical and digital channels within the same journey. Failure to deliver can cost dearly ...

If your best engineers spend their days sorting tickets and resetting access, you are wasting talent. New global data shows that employees in the IT sector rank among the least motivated across industries. They're under a lot of pressure from many angles. Pressure to upskill and uncertainty around what agentic AI means for job security is creating anxiety. Meanwhile, these roles often function like an on-call job and require many repetitive tasks ...