Thanks, that led me right to the problem. There were three nameservers listed in my resolv.conf file. The ip address listed in the error was the third. Both it and the second server listed responded correctly to dns lookups using nslookup. The first server in the list however, was not responding at all to dns lookups. I replaced the dns servers with 8.8.8.8 and 8.8.4.4, and configuration now completes.