ns1.csiro.au has one IP number , which also has a corresponding reverse pointer. csiro.au, ivec.org, gcte.org, e-hrc.net, csiro.org and at least 100 other hosts use this as a nameserver. csiro.au is a domain controlled by seven nameservers. Some of them are on the same IP network. Incoming mail for csiro.au is handled by two mailservers at csiro.au themselves. They are on different IP networks. csiro.au has one IP number. ns1.csiro.au is hosted on a server in Australia.