AS21301
Natwest Markets PLC
Reputation · trust score
A transparent 0–100 signal. Every entity starts at a neutral baseline of 65; threat-intel blocklists, exposure, reverse-DNS, routing and allocation each adjust it up or down. Higher is more trustworthy.
- Baseline (neutral) 65
- Multiple-origin (MOAS) routing anomaly −12
- Trust score 53 / 100
Experimental · trust-vectors model v1.1.0 — a transparent heuristic, not a definitive verdict. How it works →
⚠ 4 MOAS prefixes — multiple origin ASNs detected
All MOAS anomalies →A previously stable prefix originated by AS21301 is now also announced by another ASN (MOAS — Multiple-Origin AS), detected from our RIPE RIS collectors. Often benign (anycast, multi-homing, or a recent transfer) — but it can signal a route leak or prefix hijack, so it's worth inspecting.
| Prefix | Origin ASNs | Last detected (UTC) |
|---|---|---|
| 155.136.202.0/23 | AS21054, AS21301 | 2026-07-23 19:08:41 |
| 155.136.200.0/23 | AS21054, AS21301 | 2026-07-22 23:23:24 |
| 155.136.146.0/24 | AS21054, AS21301 | 2026-07-22 01:53:16 |
| 155.136.144.0/24 | AS21054, AS21301 | 2026-07-22 01:53:16 |
AS21301 — global IP footprint
Cities where AS21301 has measurable IPv4 allocation. Click any dot to open that city's page. Size and color scale with IP count.
Top CIDR ranges
| CIDR | IPs | PTR Density | Organization | Country | State | City |
|---|---|---|---|---|---|---|
| 155.136.56.0/22 | 1.0K |
0.0%
|
Natwest Markets PLC | GB | — | — |
| 155.136.200.0/23 | 512 |
0.0%
|
Natwest Markets PLC | GB | Scotland | Edinburgh |
| 155.136.144.0/24 | 256 |
0.0%
|
Natwest Markets PLC | GB | — | — |
| 155.136.146.0/24 | 256 |
0.0%
|
Natwest Markets PLC | GB | — | — |
| 155.136.151.0/24 | 256 |
0.0%
|
Natwest Markets PLC | GB | — | — |
BGP Announced Prefixes
Live BGP anomalies →Prefixes AS21301 actually originates in BGP, observed across our RIPE RIS collectors. This live routing view can differ from the registry allocation above.
| Prefix | Announcement samples | Last seen |
|---|---|---|
| 155.136.56.0/22 | 7,059 | 2026-07-23 17:51:10 |
| 155.136.59.0/24 | 6,504 | 2026-07-23 17:51:12 |
| 155.136.58.0/24 | 6,501 | 2026-07-23 17:51:12 |
| 155.136.57.0/24 | 6,492 | 2026-07-23 17:51:12 |
| 155.136.56.0/24 | 6,491 | 2026-07-23 17:51:12 |
| 155.136.201.0/24 | 5,871 | 2026-07-23 17:51:12 |
| 155.136.200.0/24 | 5,853 | 2026-07-23 17:51:12 |
| 155.136.151.0/24 | 5,844 | 2026-07-23 17:51:12 |
| 155.136.202.0/23 | 5,828 | 2026-07-23 17:20:28 |
| 155.136.200.0/23 | 5,054 | 2026-07-23 17:51:22 |
| 155.136.146.0/24 | 2,179 | 2026-07-23 17:51:12 |
| 155.136.144.0/24 | 2,173 | 2026-07-23 17:51:12 |
Frequently Asked Questions
What is AS21301?
AS21301 is an Autonomous System Number assigned to Natwest Markets PLC. An ASN identifies a network that controls a specific set of IP addresses and determines how traffic is routed across the internet via BGP (Border Gateway Protocol).
How many IP addresses does AS21301 announce?
AS21301 announces 2.3K IPv4 addresses distributed across 5 routed CIDR prefixes. The network is registered in United Kingdom.
Who operates AS21301?
AS21301 is operated by Natwest Markets PLC. The organization is based in United Kingdom. You can view all IP ranges and related ASNs on the organization page.
What country is AS21301 registered in?
AS21301 is registered in United Kingdom. This indicates where the network operator is headquartered, though the IP addresses it announces may serve users globally.
