A system for detecting a computing device tethered to a mobile device is described. The system includes communicatively coupled the computing device to the mobile device with an IPv4 domain protocol. Additionally, the mobile device is communicatively coupled to the mobile data network with an IPv6 domain protocol. A network module, associated with a mobile data network, receives a DNS request packet from the mobile device. An IPv6 hostname and an IPv6 destination address is associated with the DNS response packet, when the DNS response packet is associated with the IPv6 address. Additionally, an IPv4 hostname and an IPv4 destination address is associated with the DNS response packet, when the DNS response packet is associated with the IPv4 address. A communication packet, generated by the mobile device, is also received by the network module. The communication packet includes a destination address and a hostname. The computing device is tethered to the mobile device when the destination address matches the IPv4 destination address and the hostname does not match the IPv6 hostname.