Autonomous system
AS10000 NCM Nagasaki Cable Media Inc.
Residential RIPE Cable/DSL/ISP
Summary
Nagasaki Cable Media Inc.
NCM is Nagasaki Cable Media Inc., a community cable-television operator headquartered in Nagasaki City that sells cable TV, broadband internet, fixed-line phone and mobile service across Nagasaki, Saikai, Togitsu and Nagayo. AS10000 is the eyeball network behind that broadband product.
What it's used for
Residential and small-business cable broadband. The AS announces 20 IPv4 prefixes totalling roughly 73,700 addresses plus a single IPv6 /32, and the sampled reverse DNS is subscriber-pool naming throughout: hosts like cdu20m5.cncm.ne.jp and cmu07a5.cncm.ne.jp sit under NCM's own cncm.ne.jp service domain, with the cdu/cmu prefixes indexing cable-modem access concentrators rather than servers. Nothing in the sampled space looks like hosting or content infrastructure.
Notable
This is an eyeball network, and the routing shape says so plainly. Roughly 73,700 addresses against only 28 observed BGP neighbours is the classic access-ISP silhouette: a wholesale carrier with that much space would be peering with hundreds of ASes, whereas an access network buys transit from a couple of upstreams and peers locally. Geolocate this space to end users in western Kyushu, not to a datacentre.
Interesting
AS10000 is not carrying only NCM's own subscribers. Sampled PTRs include pl-126.52.0.5.cableone.ne.jp and pl-103.29.48.5.taku.ne.jp — CableOne (Takeo, Saga) and Taku Cable Media (Taku, Saga), two separate cable operators in the neighbouring prefecture. NCM is evidently acting as the shared ISP platform and BGP origin for smaller partner cable companies, which is a common arrangement among Japanese regional CATV operators and explains why the address space is spread across so many unrelated-looking blocks. The IP space is still eyeball space; the subscribers behind some of it just belong to a different cable company.
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
Internet exchanges
Recorded at 6 exchanges in 3 countries, largest first.
| Exchange | Location | Their address |
|---|---|---|
| BroadBand Internet eXchange Tokyo | Tokyo, Japan | 101.203.88.139 |
| JPIX Tokyo | Tokyo, Japan | 210.171.224.141 |
| BroadBand Internet eXchange Singapore | Singapore, Singapore | 103.231.152.80 |
| BroadBand Internet eXchange Osaka | Osaka, Japan | 218.100.9.34 |
| JPIX Osaka | Osaka, Japan | 103.246.232.141 |
| BroadBand Internet eXchange Hong Kong | Hong Kong, China | 103.203.158.80 |
Transit providers
11 upstream, 1 downstream and 16 adjacent networks observed; most-used upstreams first.
Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-14, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.
Address space
Summary
IPv4 19 prefixes · 73.73K addresses IPv6 1 prefixes
| Country | Name | Prefixes |
|---|---|---|
| JP | Japan | 20 |
Registry
Allocation record
- Registry
- RIPE
- Handle
AS10000- Registry name
- NCM
- Registered
- 2000-04-27
- Last changed
- 2018-03-19
- Allocation
- allocated
Declared
PeeringDB profile
- Name
- Nagasaki Cable Media
- Also known as
- ncm
- Network type
- Cable/DSL/ISP
- Scope
- Asia Pacific
- Traffic ratio
- Mostly Inbound
- Peering policy
- Open
- IRR as-set
AS-10000- Present at
- 13 exchanges
- Facilities
- 5 facilities
- Website
- https://www.cncm.ne.jp/
PeeringDB records are maintained by the network operator and are not independently verified. Treat them as a statement of intent rather than of fact. For the observed and recorded view, see peering, which lists the exchanges Packet Clearing House has a port on file for.
Routing security
RPKI and IRR
- RPKI
- 100% valid · 21 valid, 0 with no ROA
- ROAs
- 21 authorising AS10000
- ASPA
- no ASPA record
- IRR
- 90% registered · 19 of 21 announcements
- Route objects
- 31 naming AS10000
Reputation
Classification and threat
Residential Fixed-line consumer ISP. Addresses here are homes.
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: 442 networks and 1,773 prefixes, as published 2026-10-13. 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