subnet.im

AS51800FIBER Network s.r.o.

CzechiaRegistryRIPE NCC

As of 10th November 2026, AS51800 (FIBER Network s.r.o.), a network registered in Czechia with RIPE NCC, originates 1 IPv4 prefix covering 2k addresses and 1 IPv6 prefix. By IPv4 address space that makes it the 25,846th-largest of the 80,733 networks we see originating IPv4, and the 214th-largest of 576 in Czechia. It is seen behind 9 upstream networks, most often AS49025 (PRO-ZETA a.s.) and AS51400 (SPOJE.NET s.r.o.), and in front of 2 downstream networks. Every one of its announcements has a valid RPKI ROA, and none are RPKI-invalid. 100% of its routes reach at least 90% of full-feed peers.

At a glance

IPv4 prefixes

1

IPv6 prefixes

1

IPv4 addresses

2k

IPv6 /64s

4.3B

Upstream graph

The networks AS51800 is seen behind, one and two hops out, drawn from real AS paths.

AS51800Toward the internet core
Upstream graph for AS51800: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS51800FIBER Network s.r…This networkAS6939Hurricane Electri…AS24482SG.GSAS24940Hetzner Online Gm…AS49025PRO-ZETA a.s.AS51400SPOJE.NET s.r.o.AS20130Depaul UniversityAS132337AxclusiveAS38623Metfone (Viettel …AS215859Hetzner Cloud - S…AS3356Lumen (Level 3)AS39392SH.cz s.r.o.AS8251FreeTel, s.r.o.

Networks observed one and two hops upstream of AS51800 in real AS paths. A thicker line means more vantage points saw that adjacency, so weight tracks how well attested it is — not how much traffic it carries. Adjacency is an observation; whether it is a transit purchase or a settlement-free peering is an inference, and is labelled as one wherever we show it.

Neighbouring networks

38

adjacent networks

Upstreams
924%
Peers
2771%
Downstreams
25%

Networks carrying this one's traffic toward the rest of the internet.

Upstreams of AS51800
NetworkCountryRelationshipPathsVantage pts
AS49025PRO-ZETA a.s.CZPeer129101
AS51400SPOJE.NET s.r.o.CZPeer1818
AS6939Hurricane Electric LLCUSPeer77
AS24482SG.GSSGPeer44
AS32590Valve CorporationUSPeer22
AS24940Hetzner Online GmbHDEPeer22
AS49544i3D.net B.VNLPeer22
AS132337AxclusiveSGAdjacent11
AS22356Durand do Brasil LtdaBRPeer11

Prefixes

The largest blocks AS51800 originates, widest first.

Largest prefixes originated by AS51800
PrefixAddressesVisibility
217.28.80.0/212k75/76
2a02:28a8::/324.3B × /6463/63

Routing health

How AS51800's own announcements validate against RPKI and how far they propagate. The same measures for the whole routing table are on the routing table in numbers.

RPKI origin validation

  • Valid100.0%2
  • Invalid0.0%0
  • No ROA0.0%0

Propagation

  • Globally propagated90% of full-feed peers or more100.0%2
  • Partially propagated40% to 90%0.0%0
  • Seen by few peersUnder 40%0.0%0

Prefix sizes

IPv4 — 1 prefixes

IPv6 — 1 prefixes

  • /324.3B × /64100.0%1

Recent changes

Announcements that started or stopped since 12th Oct 2026.

No announcement by AS51800 started or stopped in this period.

Routing data derived from RouteViews MRT archives, BGPKIT relationship inference and public registry data.