Please refer to eduroam Blog article:

https://community.jisc.ac.uk/blogs/eduroam/article/advisory-improving-efficiency-international-authentication-through-utilisation

If you employ MS Windows 2008R2 DNS Server you may also find the following useful:

https://community.jisc.ac.uk/groups/eduroam/document/naptr-record-creation-using-microsoft-windows-2008-r2-dns-server