Uninet (Telmex) IP Ranges
Uninet S.A. de C.V. is the carrier subsidiary that runs Telmex's IP network, and AS8151 is the system it announces from. LACNIC registered the ASN on 29 April 1997 to Uninet S.A. de C.V., at an address on Avenida Insurgentes Sur in Tlalpan, Mexico City, with the technical and abuse role held by one contact at gccips@uninet.com.mx, listed at Torre Telmex. Its PeeringDB record gives telmex.com as the website, AS-8151 as the IRR as-set and an open peering policy, and types the network as network services rather than as an ISP. Retail broadband is sold over it under the Infinitum brand, and the reverse DNS says so on the addresses that carry one.
- Provider
- Uninet (Telmex)
- Primary ASN
- AS8151
- Category
- ISP
- Headquarters
- Mexico City, Mexico
- Announced IPv4 prefixes
- 12948
- Registry
- LACNIC
Known IP ranges
These prefixes are currently announced to the global routing table by AS8151 (AS8151 - UNINET). Prefix sets change over time - use WHOIS Lookup for the authoritative record on any specific address.
201.100.0.0/16
201.122.0.0/16
148.212.0.0/16
201.153.0.0/16
201.109.0.0/16
148.217.0.0/16
201.99.0.0/16
148.219.0.0/16
187.203.0.0/16
201.101.0.0/16
2806:1070::/32
2806:1080::/32
2806:1000::/32 (IPv6)
What does a Uninet (Telmex) IP mean in a privacy test?
An AS8151 address is a Mexican line answering directly, but being announced by Telmex is not the same as being registered to Telmex, and on this network the gap is wide. Three of the ten largest prefixes AS8151 announces are 148.212.0.0/16, 148.217.0.0/16 and 148.219.0.0/16, and LACNIC records all three as assignments made in 1992 to Universidad Autonoma de Coahuila, Universidad Autonoma de Zacatecas and Universidad Autonoma de Tlaxcala respectively, with no origin ASN on the record and reverse nameservers the registry itself flags as lame. Space Uninet actually holds reads differently: 201.96.0.0/12 comes back as ALLOCATED to Uninet, registered in November 2005, with AS8151 named on the object. So before you treat an address here as a Telmex subscriber, check the RDAP registrant and not just the announcing ASN. The reverse DNS supplies the rest, with prod-infinitum.com.mx for residential lines, prod-empresarial.com.mx for business circuits and uninet-ide.com.mx for assigned and customer hosts.
What Uninet publishes and what the registry adds
Uninet publishes no geolocation feed. The LACNIC RDAP record covering 201.100.10.20 is the allocation 201.96.0.0/12, registered on 14 November 2005 and last changed on 27 September 2021, with a single contact holding the administrative, technical and abuse roles and a remarks field that repeats the network line and nothing else. There is no geofeed link on it. What the record does add is two LACNIC-specific fields: lacnic_originAutnum, which names AS8151 on the object itself, and lacnic_reverseDelegations, which lists the reverse zones. Both are useful precisely because they are absent from the university blocks AS8151 also announces.
Read that delegation list carefully, because it invites an inference it does not support. The 201.96.0.0/12 is delegated as sixteen separate /16 entries, and every one of the sixteen points at the same three nameservers, NSMEX2, NSGDL2 and NSMTY2 under UNINET.NET.MX, differing only in the order they are listed. The labels match the airport codes for Mexico City, Guadalajara and Monterrey, but because all three serve all sixteen blocks they record where Uninet runs nameservers and say nothing about where any block is used. For routing, the PeeringDB record names AS-8151 as the IRR as-set with an open peering policy, and that as-set is the machine-readable object to build prefix lists from. For anything about a particular address, the reverse name is the operator's most detailed public statement and the RDAP registrant is the check on it.
Reading a Uninet hostname, and when not to trust the ASN
Three zones carry almost all of it, and the octet order is not consistent between them. prod-infinitum.com.mx is residential: 187.222.10.20 answers as dsl-20-10-222-187-dynamic.prod-infinitum.com.mx with the address backwards, while 201.102.10.20 answers as acceso-201.102.10.20.prod-infinitum.com.mx with dots inside the label. prod-empresarial.com.mx is the business side, as in dsl-201-100-10-20-sta.prod-empresarial.com.mx, where sta is short for static and the address runs forwards. uninet-ide.com.mx holds assigned and customer hosts, as in customer-189-240-10-20.uninet-ide.com.mx and host-20-10-static-153-201.uninet-ide.com.mx. Read the words, not the digits.
A label containing dynamic is an address handed out and reclaimed, so two sightings days apart are weak evidence of the same household, while static or the -sta suffix marks an address meant to stay put and worth treating as an identifier. Hosts under uninet-ide.com.mx are the ones most likely to be answering inbound connections rather than originating browsing. Silence means something specific here: the three university /16s returned no reverse name at all when sampled, which fits a registry record that delegates them to nameservers LACNIC marks as lame. And a Mexican address carrying none of these zones is very likely not Uninet at all: 187.190.20.30 answers as fixed-187-190-20-30.totalplay.net on AS22884, and 201.141.30.40 as customer-201-141-30-40.cablevision.net.mx on AS28548.
Related tools
Frequently asked questions
Is every prefix AS8151 announces registered to Telmex?
No, and three of its ten largest are not. LACNIC records 148.212.0.0/16 as an assignment to Universidad Autonoma de Coahuila, 148.217.0.0/16 to Universidad Autonoma de Zacatecas and 148.219.0.0/16 to Universidad Autonoma de Tlaxcala, all made in 1992, all with no origin ASN on the record, and none of them returned a reverse name when sampled. Telmex announces the routes; the registry holder is somebody else, so check the RDAP registrant before calling an address a Telmex subscriber.
What does Infinitum mean in a Telmex hostname?
Infinitum is Telmex's retail broadband brand, and prod-infinitum.com.mx is the reverse DNS zone Uninet uses for residential lines. Business circuits get prod-empresarial.com.mx instead, and assigned or customer hosts get uninet-ide.com.mx, so the zone in the hostname is a direct statement of which product the address was provisioned under.
Why do the octets in a Uninet hostname look backwards?
Because Uninet does not use one convention. The residential DSL form writes the address in reverse, as in dsl-20-10-222-187-dynamic.prod-infinitum.com.mx for 187.222.10.20, the business form writes it forwards, as in dsl-201-100-10-20-sta.prod-empresarial.com.mx for 201.100.10.20, and one residential form uses dots inside the label. Match on the zone and on the dynamic or static keyword rather than trying to parse the digits in a fixed order.
Does Telmex publish a geofeed for its address space?
No. The LACNIC RDAP records for the Uninet allocations carry no geofeed link and no per-city data, only the registrant, the dates, the origin ASN and the reverse delegations. The nameservers in that delegation are labelled NSMEX2, NSGDL2 and NSMTY2 after Mexico City, Guadalajara and Monterrey, but all three are listed on every one of the sixteen delegated blocks, so they are not a regional split and cannot be read as one.
Is every Mexican IP address starting 187 or 201 a Telmex address?
No, and assuming so is a common error. Those ranges are split across several Mexican operators: 187.190.20.30 is announced by AS22884 for Total Play and resolves under totalplay.net, while 201.141.30.40 is announced by AS28548 for Cablevision and resolves under cablevision.net.mx. Check the announcing ASN and the reverse DNS zone rather than the first octet.