More information about this security flaw is available in the following bug: https://bugzilla.redhat.com/show_bug.cgi?id=2342879 Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
This affects only dns server because the flaw happens when bind asks for answers from other dns servers/resolvers that contain more entries in rdata section which is apparently causing extra iterations/cpu consumption at the bind side, not in dhcp server updating clients' ip with bind or looking up the current records for clients.