Implement a standby database in oracle versions different 10g primary and 11 g standby, is it feasible?
It not recommend at all
If you are implementing a Physical Standby you must considering same Oracle version and edition
Oracle 10g primary with Oracle 10g standby
Oracle 11g primary with Oracle 11g standby
If you would like to mix oracle versions, editions and platformos you should look for a replication solution like Oracle GoldeGaten or Dbvisit Replicate