This disclosure describes techniques for verifying compatibility of NOS image versions during startup of one or more hardware modules of a distributed router system. A client-server transaction protocol is executed between a communication server and a communication client configured according to the protocol to run on hardware modules of a distributed router system. A communication client discovers a communication server through a handshake transaction and sends a software image signature of an NOS image version. The communication server forwards the software image signature to an NOS verification server to determine whether the software image signature is compatible. Further, the communication server instructs the communication client to cause the hardware module hosting the communication client to boot either from a network interface or from local storage, at least in part on the determination of compatibility by the verification server, reducing numbers of reboots and increasing uptime and throughput of the system.