In this scenario, a notifies both b and c after the zone is updated. Then, b checks to see whether the zone's serial number has incremented and initiates a zone transfer. However, c ignores a 's NOTIFY announcement because a is not c 's configured master name server (b is). If b is running BIND 8.2.3 or BIND 9 or is explicitly configured to notify c, then after b 's zone transfer completes, it sendsa NOTIFY announcement to c, which prompts c to check the serial number b holds for the zone. If c is also running BIND 8.2.3 or BIND 9, it sends b a NOTIFY announcement after its zone transfer finishes, which b, naturally, ignores.