An apparatus comprising: a storage device; and a processing unit communicatively coupled to the storage device, wherein the processing unit is configured to: receive at least one communication from the node within the network wherein the communication comprises at least one out-of-band list that includes a set of cookies sent by the node during a setup operation and an offset representation that identifies an offset where each cookie is located within packets received from the node; identify the set of cookies within the communication received from the node; populate the storage device with the set of cookies identified within the communication received from the node; receive from the node within the network, at least one time-synchronization packet that is formatted in a time-synchronization protocol as part of a time-synchronization operation; identify at the offset identified by the offset representation, a cookie included in the time-synchronization packet received from the node; search the set of cookies stored in the storage device for the cookie included in the time-synchronization packet received from the node; identify during the search of the set of cookies, the cookie included in the time-synchronization packet received from the node; and protect against a Denial of Service, DoS, attack by authenticating the legitimacy of the time-synchronization packet by confirming that the cookie included in the time-synchronization packet is identified in the set of cookies; and upon authenticating the legitimacy of the time-synchronization packet, synchronize the clock of the apparatus with the clock of the node based at least in part on a time-synchronization calculation that accounts for the time-synchronization packet. a storage device; and a processing unit communicatively coupled to the storage device, wherein the processing unit is configured to: receive at least one communication from the node within the network wherein the communication comprises at least one out-of-band list that includes a set of cookies sent by the node during a setup operation and an offset representation that identifies an offset where each cookie is located within packets received from the node; identify the set of cookies within the communication received from the node; populate the storage device with the set of cookies identified within the communication received from the node; receive from the node within the network, at least one time-synchronization packet that is formatted in a time-synchronization protocol as part of a time-synchronization operation; identify at the offset identified by the offset representation, a cookie included in the time-synchronization packet received from the node; search the set of cookies stored in the storage device for the cookie included in the time-synchronization packet received from the node; identify during the search of the set of cookies, the cookie included in the time-synchronization packet received from the node; and protect against a Denial of Service, DoS, attack by authenticating the legitimacy of the time-synchronization packet by confirming that the cookie included in the time-synchronization packet is identified in the set of cookies; and upon authenticating the legitimacy of the time-synchronization packet, synchronize the clock of the apparatus with the clock of the node based at least in part on a time-synchronization calculation that accounts for the time-synchronization packet. receive at least one communication from the node within the network wherein the communication comprises at least one out-of-band list that includes a set of cookies sent by the node during a setup operation and an offset representation that identifies an offset where each cookie is located within packets received from the node; identify the set of cookies within the communication received from the node; populate the storage device with the set of cookies identified within the communication received from the node; receive from the node within the network, at least one time-synchronization packet that is formatted in a time-synchronization protocol as part of a time-synchronization operation; identify at the offset identified by the offset representation, a cookie included in the time-synchronization packet received from the node; search the set of cookies stored in the storage device for the cookie included in the time-synchronization packet received from the node; identify during the search of the set of cookies, the cookie included in the time-synchronization packet received from the node; and protect against a Denial of Service, DoS, attack by authenticating the legitimacy of the time-synchronization packet by confirming that the cookie included in the time-synchronization packet is identified in the set of cookies; and upon authenticating the legitimacy of the time-synchronization packet, synchronize the clock of the apparatus with the clock of the node based at least in part on a time-synchronization calculation that accounts for the time-synchronization packet.