A first network apparatus, comprising: one or more processors; and one or more computer-readable non-transitory storage media coupled to the one or more processors and comprising instructions operable when executed by the one or more processors to cause the first network apparatus to: identify a plurality of target network apparatuses within a network to which the first network apparatus belongs; generate a first message comprising one or more headers comprising a label, wherein the one or more headers comprise: a reply-required indication; and encoded identities for the plurality of target network apparatuses; send the first message through the network, wherein the network is configured to deliver a copy of the first message to each of the plurality of target network apparatuses using a point-to-multipoint packet-forwarding architecture based on the encoded identities for the plurality of target network apparatuses, wherein the first message comprises a payload data, and wherein the payload data comprises information that uniquely identifies the first message; receive one or more second messages from one or more of the plurality of target network apparatuses, respectively, wherein each of the one or more second messages is generated as a reply to the first message by one of the one or more target network apparatuses; determine that each of the one of more second messages is a reply to the first message by comparing the payload of the first message with a payload of the second message; and identify, based on the received one or more second messages, which of the plurality of target network apparatuses failed to respond to the first message. one or more processors; and one or more computer-readable non-transitory storage media coupled to the one or more processors and comprising instructions operable when executed by the one or more processors to cause the first network apparatus to: identify a plurality of target network apparatuses within a network to which the first network apparatus belongs; generate a first message comprising one or more headers comprising a label, wherein the one or more headers comprise: a reply-required indication; and encoded identities for the plurality of target network apparatuses; send the first message through the network, wherein the network is configured to deliver a copy of the first message to each of the plurality of target network apparatuses using a point-to-multipoint packet-forwarding architecture based on the encoded identities for the plurality of target network apparatuses, wherein the first message comprises a payload data, and wherein the payload data comprises information that uniquely identifies the first message; receive one or more second messages from one or more of the plurality of target network apparatuses, respectively, wherein each of the one or more second messages is generated as a reply to the first message by one of the one or more target network apparatuses; determine that each of the one of more second messages is a reply to the first message by comparing the payload of the first message with a payload of the second message; and identify, based on the received one or more second messages, which of the plurality of target network apparatuses failed to respond to the first message. identify a plurality of target network apparatuses within a network to which the first network apparatus belongs; generate a first message comprising one or more headers comprising a label, wherein the one or more headers comprise: a reply-required indication; and encoded identities for the plurality of target network apparatuses; a reply-required indication; and encoded identities for the plurality of target network apparatuses; send the first message through the network, wherein the network is configured to deliver a copy of the first message to each of the plurality of target network apparatuses using a point-to-multipoint packet-forwarding architecture based on the encoded identities for the plurality of target network apparatuses, wherein the first message comprises a payload data, and wherein the payload data comprises information that uniquely identifies the first message; receive one or more second messages from one or more of the plurality of target network apparatuses, respectively, wherein each of the one or more second messages is generated as a reply to the first message by one of the one or more target network apparatuses; determine that each of the one of more second messages is a reply to the first message by comparing the payload of the first message with a payload of the second message; and identify, based on the received one or more second messages, which of the plurality of target network apparatuses failed to respond to the first message.