Update 9-9-92 named now supports a '-s' flag. Using it means that your secondary server supports shuffle A records, and so when sending them via the zone transfer mechanism, it will send a "SA' record instead of a plain "A" record. It also handles the case where a give domain name has some SA records and other types of records. (It shuffles the A records and leaves the rest alone.) ------------------------------------------------------------------------------ SA records are a new data type that I have added to BIND 4.8.3. They are "shuffle A records". They look and act just like A records except the nameserver shuffles them up before replying to the requester. Use SA records in cases where you would like several A records returned, but in a different order each time. There is no support in SA records for any kind of scheduling or weighting; you're stuck with randomness. The syntax of a SA record is identical to the of an A record, except that the type field is SA, not A. SA records are implemented in this way. An additional record type is defined in /usr/include/arpa/nameser.h, namely T_SA (104). In addition a new named data flag is defined, DB_F_SHUFFLE. db_load() is modified to recognize SA records. When it finds one, it sets the DB_SHUFFLE data flag of the record, but then it falls through to the standard A record code. From this point on only your nameserver knows it is a SA record; to the rest of the world (including your secondary servers) it will apeear as an A record (EXCEPTION: if you use the -s flag described above). ns_req() and ns_resp() also need to be modified to check to see if the DB_SHUFFLE flag is set on any data they are to return. If they do see the flag, then all of the A records with that flag set are shuffled. The shuffling is handled by a routine called shuffle_rrs() in a new source file ns_shuf.c. The shuffling code is simple. Records are not so much shuffled as they are re-ordered. The bind4.8.3.tar.Z release in this directory contains a BIND 4.8.3 with SA record support. I would have made some kind of diffs available, but because of the various versions of BIND floating about (4.8.1, 4.8.3, patched 4.8.3, patched and hacked 4.8.3, . . .) it really isn't very easy. Some future work might include adding SX (shuffle MX) records, getting the shuffle code to cope with non-A records, and getting named-xfer to preserve SA records in secondaries.