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Infrastructure Services Health Score Calculator

Score DNS, DHCP, NTP, AAA and syslog health into one weighted grade and flag the weakest service.

About Infrastructure Services Health Score Calculator

Each core service is scored against the threshold at which users start noticing it, then weighted by how completely its failure blocks access. DNS carries the largest weight because nothing else works without it, and AAA is close behind because a failed authentication denies the network outright. Core services fail quietly until they fail totally, so a single rolled-up grade with a weakest-service pointer gives operations somewhere to look before the pool exhausts or the clock skew breaks Kerberos.

Formula

Infrastructure Services Health Score

score = 0.30 × DNS + 0.20 × DHCP + 0.20 × AAA + 0.15 × NTP + 0.15 × syslog, each normalised to 0–100.

DNS
Sub-score falling 50 points per 1% of failed queries
DHCP
Sub-score falling 3.3 points per % of pool utilisation above 70%
NTP
Sub-score falling 4 points per ms of offset above 1 ms

Worked example

With the default values below, Infrastructure Services Health Score Calculator returns Infrastructure Health Score of 85.1. Change any input above and every figure here is recalculated in your browser.

Inputs used

DNS query success rateaccepts 90–100 %
99.9 %
DHCP pool utilisationaccepts 0–100 %
72 %
NTP offset from referenceminimum 0 ms
8 ms
AAA response latencyminimum 0 ms
45 ms
Syslog message drop rateaccepts 0–100 %
0.5 %

Results

Infrastructure Health Score
85.1 /100
Grade
B — Good
Weakest Service
AAA (RADIUS/TACACS+)
Services Below Threshold
0
DNS Sub-Score
95.0
AAA Sub-Score
70.0

Step by step

  1. 1Values used
  2. 2Infrastructure Services Health Score
  3. 3Infrastructure Health Score= 85.1 /100
  4. 4Grade= B — Good
  5. 5Weakest Service= AAA (RADIUS/TACACS+)
  6. 6Services Below Threshold= 0
  7. 7DNS Sub-Score= 95.0
  8. 8AAA Sub-Score= 70.0

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Infrastructure Services Health Score calculated?

score = 0.30 × DNS + 0.20 × DHCP + 0.20 × AAA + 0.15 × NTP + 0.15 × syslog, each normalised to 0–100. Each core service is scored against the threshold at which users start noticing it, then weighted by how completely its failure blocks access. DNS carries the largest weight because nothing else works without it, and AAA is close behind because a failed authentication denies the network outright.

Why does Infrastructure Services Health Score matter?

Core services fail quietly until they fail totally, so a single rolled-up grade with a weakest-service pointer gives operations somewhere to look before the pool exhausts or the clock skew breaks Kerberos.

What values do I need to enter?

This calculator takes 5 inputs: DNS query success rate, DHCP pool utilisation, NTP offset from reference, AAA response latency, Syslog message drop rate. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Why is 70% DHCP utilisation the penalty threshold?

Pools do not fail gracefully — once utilisation passes about 70% normal daily variation and lease overhang start producing intermittent failures for a subset of clients, which is far harder to diagnose than outright exhaustion.

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