The DOS version of tracert doesn't give the IP address of failed pings. What is a reasonably simple way to find the IP's of non-responsive servers in a traceroute?
There are none. The only trivial way would be asking the hop. Traceroute implements this by sending an ICMP echo request (pinging) the destination multiple times with different time-to-live values. Every hop decreases this counter by one. When the TTL hits zero, the packet is not relayed any further and the hop attempts to return an error message to the source, primarily to prevents packets on faulty routes from circulating indefinitely and congesting the network. By looking at the source of the returned error messages, the machine doing the traceroute can identify hops between itself and the destination.
If for whatever reason no error message is received, the fate of the echo request cannot be determined. After the first hop, the packet enters a black box and the sender has effectively no control over or information about how it is routed. Hops immediately before (and often immediately after) will know the address of the missing link, but there is no universal way to exchange this information.