AS3378 — MCI-ASN
AS3378 announces 28 IPv4 prefixes covering 64,256 addresses and 0 IPv6 prefixes.
About this network
The last of the four consecutive legacy MCI autonomous systems (MCI-ASN) held by Verizon Business, and the busiest of the group by prefix count.
What it's used for
- Announcing a broad scatter of MCI-era IPv4 blocks for Verizon Business, predominantly customer and managed-service address space.
- Backbone transit proper is carried by AS701; this ASN exists mainly to originate legacy prefixes.
Notable
- Registered to Verizon Business in Ashburn, Virginia, with an ARIN record reaching back to the mid-1990s.
- The prefixes are numerous but mostly small (many /22s and /24s) — the signature of address space handed out to individual customer sites over decades.
Interesting
- Together with AS3375, AS3376 and AS3377, it forms a contiguous four-ASN run that MCI claimed early and Verizon never retired.
This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy.
Announced prefixes
- 142.77.1.0/24
- 142.77.14.0/24
- 142.77.32.0/24
- 142.77.46.0/24
- 146.1.1.0/24
- 146.1.2.0/24
- 146.1.4.0/23
- 146.1.6.0/24
- 146.1.16.0/23
- 146.1.24.0/21
- 146.1.40.0/21
- 146.1.192.0/19
- 159.24.64.0/20
- 159.98.72.0/21
- 159.98.104.0/21
- 159.98.112.0/22
- 162.47.128.0/20
- 162.47.144.0/22
- 165.122.128.0/20
- 166.34.64.0/18
- 166.38.96.0/19
- 166.38.132.0/23
- 166.38.136.0/23
- 198.168.54.0/24
- 198.168.73.0/24
- 199.249.16.0/20
- 205.150.161.0/24
- 205.150.163.0/24
Upstream networks
- AS701 Verizon Business
Downstream networks
Adjacent networks
BGP / ASN / CIDR
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IPv4
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IPv6
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Search Results
IPv4 Prefixes
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IPv6 Prefixes
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Total Prefixes
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Unique /24s
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⚠ SUSPICIOUS PREFIX ANNOUNCEMENTS DETECTED