The Nines Scale: Every Digit Counts
In the hosting industry, availability levels are referred to as nines. Each additional nine after the decimal point reduces allowed downtime by a factor of 10 and correspondingly increases infrastructure and process requirements.
| SLA Level | Designation | Downtime/Year | Downtime/Month | Downtime/Week |
|---|---|---|---|---|
| 99% | Two nines | 87.6 hours | 7.3 hours | 1.68 hours |
| 99.5% | Two and a half nines | 43.8 hours | 3.65 hours | 50.4 minutes |
| 99.9% | Three nines | 8.76 hours | 43.8 minutes | 10.1 minutes |
| 99.95% | Three and a half nines | 4.38 hours | 21.9 minutes | 5.04 minutes |
| 99.99% | Four nines | 52.6 minutes | 4.38 minutes | 1.01 minutes |
| 99.999% | Five nines | 5.26 minutes | 26.3 seconds | 6.05 seconds |
The jump from 99.9% to 99.99% appears marginal but means a reduction in allowed downtime from 8.76 hours to 52.6 minutes per year. To achieve this level, a provider needs redundant servers, automatic failover, redundant network connectivity, and monitored infrastructure. This also explains the significant price difference between standard and premium hosting.
What Hosting Providers Typically Promise
Most German hosting providers promise 99.9% availability, some 99.95%. Only a few premium providers and cloud platforms guarantee 99.99% or higher. The crucial factor, however, is not the advertised level but the contractual definition.
Budget Shared Hosting
Shared hosting providers in the EUR 3 to 10 per month range typically offer 99 to 99.5% availability, some also 99.9%. Actual availability often falls short because shared hosting depends on the load of all co-tenants. Without independent monitoring, you cannot know whether the promised availability is being met.
Managed Hosting and VPS
Managed hosting providers and VPS solutions in the EUR 20 to 80 per month range typically promise 99.9 to 99.95%. The more dedicated resources make these promises more realistic, but even here the principle applies: trust is good, verification is better. Actual availability can fall below the SLA due to software issues, maintenance windows, and unforeseen outages.
Cloud Hosting and Enterprise
Cloud platforms and enterprise hosting in the EUR 100 to 500 per month range promise 99.95 to 99.99%. These providers have redundant infrastructure, automatic failover, and 24/7 monitoring. Nevertheless, absolute availability does not exist: even major cloud providers regularly experience outages affecting individual regions or services.
The Fine Print: What to Watch For
The advertised uptime guarantee is only as good as the contractual details behind it. The following points should be checked before signing a contract.
Definition of Downtime
How does the provider define an outage? Some providers count only complete server failures, not partial outages, extreme slowdowns, or network issues. If your website is technically reachable but takes 30 seconds to load, many providers do not count that as downtime. For your visitors and Google, however, the page is effectively unusable.
Measurement Method and Period
How is availability measured? Some providers measure only internally and do not share measurement data with customers. Others measure in intervals of 5 or 15 minutes, making short outages invisible. The measurement period is also relevant: is it calculated monthly or annually? With annual calculation, a single bad month can be offset by good months.
Exceptions and Scheduled Maintenance
Nearly all SLAs contain exceptions: scheduled maintenance windows, DDoS attacks, force majeure, and issues outside the provider's control. Some providers exclude maintenance windows of up to 4 hours per month from SLA calculations, which significantly reduces the effective guarantee. Explicitly ask about exceptions and how maintenance windows are announced.
Compensation for SLA Violations
What happens when the provider violates the SLA? Most providers offer service credits: percentage credits on the next invoice. Typically 5 to 25% of the monthly fee per hour of additional downtime. This means: even with a massive SLA violation, you receive at most one monthly fee refunded, not actual business damages. The guide to downtime costs shows how substantial the actual costs can be.
A hosting SLA does not protect you from the economic consequences of an outage. If your shop is unreachable for 4 hours and you lose EUR 912 in revenue, you receive at best EUR 20 in credit from the hoster. The ROI of monitoring lies precisely here: early detection minimizes actual damage.
Promise vs. Reality: Why Independent Monitoring Matters
The advertised uptime guarantee and actual availability are two different things. Without independent monitoring, you have no way to verify SLA compliance. You rely on the provider's measurements, and they naturally have no interest in documenting their own outages.
XICTRAQ measures your website's availability independently from multiple DACH locations and documents every outage with timestamp, duration, and HTTP status code. This data serves as the basis for SLA claims, provider switch decisions, and uptime SLA reporting.
Hosting Types and Their Typical Availability
Multiple websites share a server. Availability fluctuates depending on co-tenants. Typical: 99-99.5% effective, often advertised as 99.9%. Sufficient for non-critical websites.
Dedicated virtual resources on shared hardware. More stable than shared hosting but no hardware redundancy. Typical: 99.5-99.9% effective.
The provider handles server management and optimization. Proactive maintenance and monitoring by the provider. Typical: 99.9-99.95% effective.
Automatic failover between availability zones. Hardware failures are transparently handled. Typical: 99.95-99.99% effective.
What Actually Lies Behind the Numbers
To achieve 99.99% availability, a server may be down for a maximum of 52.6 minutes per year. This requires redundant hardware with automatic failover in under 30 seconds, redundant network connectivity through at least two independent providers, uninterruptible power supply (UPS) plus diesel generator, 24/7 on-call duty with response time under 15 minutes, and automated monitoring with alerting.
Compare these requirements with your hoster's price. A shared hosting package for EUR 5 per month cannot possibly provide this infrastructure. If such a provider promises 99.99%, that is marketing communication, not reality. Focus on the actual infrastructure, not advertising promises.
Hosting Decision: Which SLA Level Do You Need?
The right availability level depends on your website's business value. Not every website needs five-nines availability. The decision should be based on a cost-benefit analysis.
- 99% (87.6 h/year): Acceptable for hobby projects, personal blogs, and internal tools without business-critical function.
- 99.9% (8.76 h/year): The minimum standard for business websites, small shops, and company presences. Covers most SMB requirements.
- 99.95% (4.38 h/year): Recommended for websites with noticeable revenue impact, mid-sized online shops, and lead generation.
- 99.99% (52.6 min/year): Necessary for high-revenue online shops, SaaS platforms, and business-critical web applications.
- 99.999% (5.26 min/year): Enterprise level for financial services, healthcare, and critical infrastructure. Requires multi-region redundancy.
Regardless of the chosen SLA level: without independent monitoring, you can neither verify compliance nor file claims for violations. XICTRAQ's uptime monitoring provides the necessary data and calculates actual availability automatically.
Checklist for Hosting Selection
- Explicitly verify SLA level and allowed downtime
- Read the definition of downtime in the contract (complete vs. partial, latency threshold)
- Check exceptions and scheduled maintenance windows
- Understand compensation terms for SLA violations
- Question the provider's measurement method and measurement period
- Verify infrastructure details (redundancy, failover, network)
- Research reviews and independent tests
- Set up independent monitoring for verification
- Check migration options: how easy is switching providers?
- Test the provider's TTFB and performance
Ensuring and Verifying Availability Long-Term
The hosting choice is not a one-time decision. Server quality can change over time through overbooking, hardware aging, or management changes. Only continuous monitoring shows you whether your hoster keeps its promises.
XICTRAQ combines uptime monitoring, performance tracking, security scans, and SEO monitoring in a single platform. This way you detect not only outages but also performance deterioration, security vulnerabilities, and SEO issues related to hosting infrastructure. Start now with a free demo or register directly.
What does 99.9% uptime mean in concrete terms?
How do 99.9% and 99.99% differ?
How do I check if my hoster meets its SLA?
What do I get for an SLA violation?
Which uptime level does my online shop need?
Does scheduled maintenance count as downtime?
This article is based on data from: (Google).