Static Route Calculator
Build a static route from a destination and prefix, and see whether its administrative distance beats the dynamic protocol.
About Static Route Calculator
Route selection is two-stage: the longest matching prefix wins outright, and administrative distance only breaks ties between protocols offering the same prefix. Raising a static route's distance above the dynamic protocol turns it into a floating static that sits dormant until the dynamic path disappears. Getting the distance wrong is how a backup DSL static route ends up carrying production traffic, or how a supposed backup never installs at all because it was left at the default distance of 1.
Formula
Static Route
The network address is destination AND mask; the route installs when its administrative distance is lower than every competing protocol's, and longest prefix match is applied before distance.
- AD
- Administrative distance — connected 0, static 1, eBGP 20, EIGRP 90, OSPF 110, RIP 120, iBGP 200
- wildcard mask
- Inverted mask, used in ACL and route-map match statements
- floating static
- A static route given a distance above the dynamic protocol so it only acts as backup
Worked example
With the default values below, Static Route Calculator returns Network Address of 10.20.30.0. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Destination network
- 10.20.30.0
- Prefix lengthaccepts 0–32 bits
- 24 bits
- Static route administrative distanceaccepts 0–255
- 1
- Competing dynamic protocolone of eBGP (AD 20), EIGRP internal (AD 90), OSPF (AD 110), IS-IS (AD 115), RIP (AD 120), iBGP (AD 200)
- OSPF (AD 110)
Results
- Network Address
- 10.20.30.0
- Subnet Mask
- 255.255.255.0
- Wildcard Mask
- 0.0.0.255
- Which Route Installs
- Static route installs — AD 1 beats 110
- Acts as a Floating Static
- No — it is the preferred path while the next hop is reachable
- Administrative Distance Used
- 1
Step by step
- 1Values used
- 2Static Route
- 3Network Address= 10.20.30.0
- 4Subnet Mask= 255.255.255.0
- 5Wildcard Mask= 0.0.0.255
- 6Which Route Installs= Static route installs — AD 1 beats 110
- 7Acts as a Floating Static= No — it is the preferred path while the next hop is reachable
- 8Administrative Distance Used= 1
Assumptions and limits
- The result is derived only from the 4 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 whole numbers, 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 Static Route calculated?
The network address is destination AND mask; the route installs when its administrative distance is lower than every competing protocol's, and longest prefix match is applied before distance. Route selection is two-stage: the longest matching prefix wins outright, and administrative distance only breaks ties between protocols offering the same prefix. Raising a static route's distance above the dynamic protocol turns it into a floating static that sits dormant until the dynamic path disappears.
Why does Static Route matter?
Getting the distance wrong is how a backup DSL static route ends up carrying production traffic, or how a supposed backup never installs at all because it was left at the default distance of 1.
What values do I need to enter?
This calculator takes 4 inputs: Destination network, Prefix length, Static route administrative distance, Competing dynamic protocol. 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 does my /32 static beat a more specific OSPF route?
It probably is not more specific. Longest prefix match runs first, so a /32 static always beats an OSPF /24 regardless of distance — distance is only consulted when the prefixes are identical.