Infrastructure Services Health Score Calculator
Score DNS, DHCP, NTP, AAA and syslog health into one weighted grade and flag the weakest service.
Inputs
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
Values used
DNS query success rate = 99.90 %; DHCP pool utilisation = 72 %; NTP offset from reference = 8 ms; AAA response latency = 45 ms; Syslog message drop rate = 0.5000 %
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.
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
How it works
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
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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