I want to test the fragmentation and under mongodb replication set functions, config server has three: port 27021,27022,27023 . I also tested when the config server down what will happen. after test is complete .I start three config server , when I start mongos like this :

1. mongos --configdb social-11:27021,social-11:27022,social-11:27023 --port 40000

I got this error：

Wed Sep 11 14:04:05.705 [mongosMain] MongoS version 2.4.6 starting: pid=27636 port=40000 64-bit host=bj-social-11 (--help for usage)
Wed Sep 11 14:04:05.705 [mongosMain] git version: b9925db5eac369d77a3a5f5d98a145eaaacd9673
Wed Sep 11 14:04:05.705 [mongosMain] build info: Linux ip-10-2-29-40 2.6.21.7-2.ec2.v1.2.fc8xen #1 SMP Fri Nov 20 17:48:28 EST 2009 x86_64 BOOST_LIB_VERSION=1_49
Wed Sep 11 14:04:05.706 [mongosMain] options:

{ configdb: "social-11:27021,social-11:27022,social-11:27023", port: 40000 }

Wed Sep 11 14:04:05.735 [mongosMain] warning: config servers social-11:27021 and social-11:27023 differ
Wed Sep 11 14:04:05.738 [mongosMain] warning: config servers social-11:27021 and social-11:27023 differ
Wed Sep 11 14:04:05.740 [mongosMain] warning: config servers social-11:27021 and social-11:27023 differ
Wed Sep 11 14:04:05.742 [mongosMain] warning: config servers social-11:27021 and social-11:27023 differ
Wed Sep 11 14:04:05.742 [mongosMain] ERROR: could not verify that config servers are in sync :: caused by :: config servers social-11:27021 and social-11:27023 differ
chunks: "03e366169519413a151a30ec70f2e87b" chunks: "03e366169519413a151a30ec70f2e87b"
databases: "a374f6b9385551520d0132ce09e5e442" databases: "b0a287b335f0ecb537855003acf5dfce"
Wed Sep 11 14:04:05.742 [mongosMain] configServer connection startup check failed

please tell me how to solve it? thanks