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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 today operate in a real-time environment where uninterrupted access to trusted data has become a baseline expectation for users, applications and automated systems. Traditional DataOps models, built on manual effort and human triage, cannot keep pace with this always active demand. AI agents are emerging as the operational backbone, ensuring consistent data availability, reinforcing trustworthiness and enabling a level of scale that manual processes cannot achieve ...

For decades, trust in the digital workplace rested on familiar signals. We trusted faces on video calls, voices on the phone, and emails that appeared to come from people we knew. These cues felt human and intuitive. They anchored how decisions were made, approvals were granted, and access was authorized. AI-powered deepfakes have quietly broken that model ...

Cloud migration was supposed to be a one-way door. For most enterprises, it turns out it isn't. Cloud data repatriation is a real and growing trend. A new survey ... finds that 89% of organizations plan to expand their on-premises infrastructure footprint over the next two years — and 75% have already moved at least some workloads back from public cloud in the past 24 months. The findings point to a broad rethinking of where data belongs ...

Over the past few years, large language models (LLMs) have revolutionized the software industry. Given their ability to excel at multi-step reasoning, LLMs have helped enterprises streamline workflows and adapt to the unknown. However, employing such models comes with sky-high costs, latency issues, and limited flexibility. In the realm of IT operations, it is generally wiser to employ smaller, domain-specific models instead ...

For years, DevOps teams operated under a simple assumption: collect enough telemetry, and you can find and fix any problem. That assumption is breaking down. Modern enterprises now operate across microservices, hybrid cloud environments, APIs, Kubernetes, and highly automated delivery pipelines. Releases happen continuously, dependencies shift constantly, and failures spread faster than teams can diagnose them ...

New Relic surveyed IT and engineering leaders from the media and entertainment (M&E) sector to understand what's working — and where challenges persist with their observability practices. The findings reveal how M&E organizations are navigating rising platform complexity, audience expectations, and AI-driven change. Below are five takeaways that stand out ...

Let me start with something I've seen play out more times than I can count. A team hits a wall with the cloud. Costs creep up, then spike. Performance starts to feel inconsistent. Someone in finance asks a simple question like "why did this double?" and nobody has a clean answer ... Maybe this isn't the right place for everything. That realization feels like a breakthrough, like you've identified the problem. In reality, you've just identified the starting line ...

In MEAN TIME TO INSIGHT Episode 24, Shamus McGillicuddy, VP of Research, Network Infrastructure and Operations, at EMA discusses network observability tool sprawl ... 

In cloud-native systems, scaling is often as simple as moving a slider. For on-premise databases, the stakes are different. Over-provisioning hardware is expensive. Under-provisioning leads to performance bottlenecks that are difficult to fix once the equipment is in the rack ...

When most people think about cybersecurity, they picture firewalls, encryption, and access controls — technical tools designed to protect systems and data. But beneath the technology lies a deeper set of principles about trust, decision-making, and resilience ... The best leaders don't eliminate risk. They manage it intelligently. And in many ways, cybersecurity offers a surprisingly useful playbook for doing exactly that ...