|A balance method is an algorithm for selecting the best
Following are the different types of balance methods:
'other' : The value 'other' has been provided
so that the MIB may still be valid
while new states emerge and the MIB
has not been updated to enumerate
'orderedList' : In this type, each resource within
an answer group (for example, an SLB
VIP or a name server) is assigned a
number that corresponds to the rank
of that answer within the group.
The number assigned represents the
order of the answer on the list.
Subsequent VIPs or name servers on
the list will only be used if
preceding VIPs or name servers on
the list are unavailable.
'roundRobin' : In this type, each resource within
an answer group is tried in turn.
The GSLB device cycles through the
list of answers, selecting the next
answer in line for each request.
In this way, the device can resolve
requests by evenly distributing the
load among possible answers.
'weightedRR' : In this type, as performed by the
round-robin balance method, the
weighted round-robin method also
cycles through a list of defined
answers to choose each available
answer in turn. However, with
weighted round-robin, an additional
weight factor is assigned to each
answer, biasing the GSLB device
towards certain servers so that
they are used more often.
'leastLoaded' : In this type, the GSLB device
resolves requests to the least
loaded of all resources.
'hashed' : In this type, elements of the
client's DNS proxy IP address and
the requesting client's domain are
extracted to create a unique value,
referred to as a hash value. The
unique hash value is attached to
and used to identify a VIP that is
chosen to serve the DNS query.
'boomerang' : This method is based on the concept
that instantaneous proximity can be
determined if a CRA within each
data center sends an A-record
(IP address) at the exact same time
to the client's D-proxy. The DNS
race method of DNS resolution gives
all CRAs (Cisco content engines or
content services switches) a chance
at resolving a client request and
allows for proximity to be determined
without probing the client's D-proxy.
The first A-record received by the
D-proxy is, by default, considered
to be the most proximate.