Well, the most specific prefix wins in the forwarding
selection process, but I won't make any comments on
"best current practice" since "best" is somewhat
relative to the idea of max-aggregation ....but
this reference might help:
G. Huston
Request for Comments: 3221
Commentary on Inter-Domain Routing in the Internet
ftp://ftp.rfc-editor.org/in-notes/rfc3221.txt
[snip]
5.4 Lack of Common Operational Practices
There is considerable evidence of a lack of uniformity of operational
practices within the inter-domain routing space. This includes the
use and setting of prefix filters, the use and setting of route
damping parameters and level of verification undertaken on BGP
advertisements by both the advertiser and the recipient. There is
some extent of 'noise' in the routing table where advertisements
appear to be propagated well beyond their intended domain of
applicability, and also where withdrawals and advertisements are not
being adequately damped close to the origin of the route flap. This
diversity of operating practices also extends to policies of
accepting advertisements that are more specific advertisements of
existing provider blocks.
[snip]
- ferg