Да эт понимаю что не нужен.Тут просто провайдер марштутизирует адрес и утверждает что backresolv не обязателен.
ftp://ftp.ripe.net/ripe/docs/ripe-185.txt
5.2. Reverse Address Delegation and Mapping
Just as it is necessary to obtain the IP number for
a host with a given domain name, it is often neces-
sary to do the reverse, that is to obtain the domain
name associated with a specific IP address. Simple
authorisation checks used by some Internet applica-
tions and some diagnostic services need the fully
qualified domain name associated with an address,
for example. Given an IP address, the procedure
used to obtain the domain name associated with it is
called reverse mapping. The RIPE NCC recommends
that Registries set up reverse delegation services
for all of the addresses assigned for their own
infrastructure and to their customers.
Разве это не рекомендация к backresolv для всех маршрутизируемых ип ?
