asn.dev

Autonomous system

AS12156 AURORA-COLORADO

Unclassified ARIN

IPv4 addresses 1.54K 5 prefixes
IPv6 prefixes 0 counted as prefixes, not addresses
Countries 1 mostly US
Exchanges 0 recorded by PCH
Upstreams 3 0 downstream
Flagged prefixes 0 none

Summary

City of Aurora, Colorado

United States · AI-generated

government legacy

The network of Aurora, Colorado, the large suburban city east of Denver.

What it's used for

  • Municipal government systems. 1,536 addresses over five prefixes with three observed BGP neighbours, no IPv6 announced.

Notable

  • The netnames are numbered in sequence — AURORA-CO1 through AURORA-CO5 — one per application, in the order they were made.
  • The registrant name changes partway through the sequence. CO1 and CO2 read "CITY OF AURORA" in capitals; CO3, CO4 and CO5 read "City of Aurora Colorado".
  • Reverse DNS answers under ci.aurora.co.us, with names like 198-199-187-64.dia.static.ci.aurora.co.us.

Interesting

  • That domain is the interesting survival. ci.<city>.<state>.us was the delegated namespace for US local government, defined when the .us hierarchy was organised geographically and every town was meant to have a place in it. Almost every city abandoned it for .gov or a plain .org, and finding one still publishing reverse DNS under the old form is rare.
  • Five sequentially numbered netnames is a small municipal IT department's history in one field. Nobody plans an address space in five instalments; each number is a separate moment when a department, a building or a service needed addresses and someone filed for more.

This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy. Source, and how to suggest an edit.

Interconnection

Peering at a glance

Full topology · Graph

Internet exchanges

No exchange port on file. Many exchanges publish no participant list, so this is not proof of absence.

Transit providers

3 upstream, 0 downstream and 3 adjacent networks observed; most-used upstreams first.

ASNetworkPaths seen
AS33652Comcast Cable Communications, LLC158
AS209CenturyLink Communications, LLC147
AS13649Flexential Colorado Corp.61

Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-31, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.

Address space

Summary

Shape and geography

IPv4 5 prefixes · 1.54K addresses IPv6 0 prefixes

CountryNamePrefixes
USUnited States of America5

Registry

Allocation record

ARIN · via Atlas (registry + RDAP)
Registry
ARIN
Handle
AS12156
Registry name
AURORA-COLORADO
Registrant
City of Aurora Colorado
Abuse contact
smnewman@auroragov.org
Registered
2018-01-24
Last changed
2018-01-24
Allocation
assigned

Routing security

RPKI and IRR

Full detail
RPKI
0% valid · 0 valid, 6 with no ROA
ROAs
0 authorising AS12156
ASPA
no ASPA record
IRR
100% registered · 6 of 6 announcements
Route objects
5 naming AS12156

Reputation

Classification and threat

Unclassified Not in the curated lists. Most of the ~80,000 allocated ASNs are not.

Spamhaus DROP

Not on ASN-DROP The network as a whole is not listed.

No DROP prefixes None of its announced space is on the DROP prefix list.

Spamhaus DROP ("Don't Route Or Peer") lists space and networks run by, or hijacked for, spam and cybercrime operations: 447 networks and 1,843 prefixes, as published 2026-11-01. A short, high-confidence list, so a match is worth taking seriously, and absence from it says little on its own.

FBI IC3

No IC3 indicators Nothing from the FBI IC3 feed.

IC3 threat data is alpha. Absence of an indicator is not evidence of good behaviour, only of absence from this one feed.

Elsewhere

Cross-check