My MongoS servers are not staring they are sending this error in logs.

SHARDING [Balancer] caught exception while doing balance: Server's sharding metadata manager failed to initialize and will remain in this state until the instance is manually reset :: caused by :: HostNotFound: unable to resolve DNS for host confserv_1.xyz.com

2016-05-02T17:57:06.612+0530 I SHARDING [Balancer] about to log metadata event into actionlog: { _id: "DB2255-2016-05-02T17:57:06.611+0530-5727479aa1051c5fb04fcc49", server: "mongoS1", clientAddr: "", time: new Date(1462192026611), what: "balancer.round", ns: "", details:

{ executionTimeMillis: 35, errorOccured: true, errmsg: "Server's sharding metadata manager failed to initialize and will remain in this state until the instance is manually reset :: caused by :: HostNotFoun..." }

}

When I connect config server using host name it is working fine.
I tried to restart MongoS server it is not coming up.

Thanks
Virendra Agarwal