The more recent versions of Solaris come with an online patching utility smpatch. This requires access to various servers on the public Internet. I cannot find any definitive documentation on exactly which servers are accessed, the documentation only suggests updates.sun.com, but this is patently not the whole story. There seems to be a system of redirects and load balancers in place that mean a bunch of other servers might be queried as well. This makes creating outbound firewall rule sets difficult.
So far I have made up the following list. The /24 networks are not entirely necessary, but I'd rather be a little generous here than having to add IPs to my rule set every time I want to patch. Access does seem to be restricted to port 443.
72.5.124.61 80.231.19.70 80.231.19.71 195.176.255.0/24 198.232.168.0/24