AS13380 — ASN-CUST

AS13380 announces 5 IPv4 prefixes covering 6,912 addresses and 1 IPv6 prefixes.

About this network

The same reverse name is attached to addresses in two different blocks, and one of them is a customer's own brand.

What it's used for

• The network of a secure email and messaging provider. 6,912 addresses across five IPv4 prefixes, four observed BGP neighbours, and the IPv6 block 2620:12d:6000::/47.

Notable

• Netnames span four company identities: VZ-63-71-8-0 and ZIXCORP, CM2-A-BLK-1 registered to a content management corporation, and LVLT-APPRI-1-8-19-116 on two blocks registered to a third company.
• Sampled names include the literal words network.zixcorp.com and broadcast.zixcorp.com.
• network.zixcorp.com answers for addresses in two different prefixes.
• Another name reads securemail- followed by a law firm's own domain.

Interesting

• One reverse name serving two addresses in unrelated blocks is allowed by the protocol and breaks the assumption almost every tool makes, which is that a reverse lookup identifies a single host. Here it identifies a role that exists once per block.
• Naming network and broadcast addresses with those exact words is a habit from hand-built zones, preserved into a network large enough that everything else is generated.
• The customer's domain appearing inside the provider's address space is how hosted secure email works: the recipient sees the sender's brand, and the address underneath belongs to the platform.
• Two carrier-formatted netnames mean two of these blocks were never held directly but assigned by upstreams, and the acquisitions since have left four names in one routing table entry set.

This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy.

Announced prefixes

• 8.19.116.0/23
• 8.19.118.0/24
• 63.71.8.0/21
• 199.30.232.0/21
• 207.195.176.0/21
• 2620:12d:6000::/47

Upstream networks

• AS6461 Zayo Bandwidth
• AS11427 Charter Communications Inc
• AS3356 Level 3 Parent, LLC

Downstream networks

• AS53780 APPRIVER LLC

Adjacent networks

• AS6461 Zayo Bandwidth
• AS11427 Charter Communications Inc
• AS3356 Level 3 Parent, LLC
• AS53780 APPRIVER LLC