UDP checks from the Madrid node send a probe to the target port and report whether a response was received. From Madrid, UDP paths to European destinations carry the same latency characteristics as ICMP — roughly 25ms to Paris, 30ms to Frankfurt. For UDP-based services targeting Spanish users, such as gaming servers, VoIP infrastructure, or WireGuard endpoints, a UDP check from this node gives a real-world view of what Spanish users would experience.

Spain's submarine cable connections to Latin America also carry UDP traffic, making the Madrid node a useful test point for UDP-based services with LATAM coverage. DNS anycast nodes, CDN UDP acceleration, and QUIC-based services that need to reach Brazilian or Mexican users often route through Spanish infrastructure. A UDP probe from Madrid to those services tests the European side of the path from a relevant geographic origin.

UDP probes that receive no response from the Madrid node are ambiguous: the target may not be running a service on that port, the port may be firewalled, or the application may simply not respond to arbitrary UDP payloads (WireGuard and many custom protocols behave this way). Cross-referencing a failed UDP check with a TCP check to a known open port on the same host confirms whether the host is up and reachable, separating UDP-specific filtering from general unreachability.

Spain has a single node on this platform: Madrid, on AS202673, operated by Ohz Digital SL. Madrid is the primary internet hub for the Iberian Peninsula, home to ESPANIX and the DE-CIX Madrid peering point. The Spanish internet backbone is largely centralised in Madrid, with Barcelona as a secondary hub via CATNIX. For most international routing purposes, traffic in and out of Spain passes through Madrid.

Spain's geographic position gives it a unique role in European networking — it sits at the junction between Europe, North Africa, and Latin America. Several submarine cables connect Spain to the Americas, and Spanish carriers maintain direct relationships with major Latin American network operators. Madrid is the natural European gateway for traffic destined for Brazil, Argentina, Mexico, and the rest of LATAM, and CDN operators frequently use Spanish nodes as part of their LATAM serving strategy.

ESPANIX in Madrid is the primary Spanish IXP and handles the bulk of domestic peering between Spanish ISPs and content providers. DE-CIX operates a separate peering node in Madrid that connects Spanish networks to DE-CIX's broader European fabric, giving Madrid-connected networks access to thousands of peers across the DE-CIX platform without needing direct bilateral agreements. CATNIX in Barcelona serves Catalan and northeastern Spanish networks.

Latency from Madrid to the rest of Europe reflects the country's southwestern position. Madrid to Paris is typically around 25ms; Madrid to Frankfurt runs about 30ms; Madrid to Amsterdam is closer to 35ms. These are noticeably higher than intra-core-Europe numbers like Frankfurt to Amsterdam (9ms), simply because of the physical distance through France. To the US East Coast, Madrid shows RTTs around 100–110ms.

Ohz Digital SL is a Spanish hosting and transit provider operating in the Madrid market. The AS202673 network connects to Spanish and international transit providers and peers at ESPANIX and DE-CIX Madrid. Tests from this node reflect conditions typical of a mid-tier Spanish hosting ASN — useful for gauging reachability from Spanish commercial hosting infrastructure without the skew of a major incumbent like Telefónica.