When two routing domains are connected by a single ASBR and it's doing redistribution, we cannot do path manipulation for redistributed routes, because there is only one point of redistribution.
When two or more ASBRs are doing redistribution between IGPs, we can do path manipulation.
Path manipulation can be useful for symmetric routing, load sharing, etc.
The following are methods for path manipulation:
When any IGP has two or more ASBRs redistributing routes into it, changing the metric values for the same routes on the different ASBRs can cause one ASBR to be preferred over the other(s).
Metric can be changed by using route-map, the metric value in the redistribute command, or the default-metric command (for some IGPs).
When routes are being redistributed into OSPF, metric-type can also be changed, by using route-map or by changing it directly with the redistribute metric-type command.
By default, all routes are redistributed as E2 routes.
E1 routes are preferred over E2 routes, irrespective of the cost of the route.