These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 0.98 s (backtrack: 0/20).

[ebuild  N     ] acct-group/rbldns-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-user/rbldns-0-r3::gentoo  0 KiB
[ebuild  N     ] net-dns/rbldnsd-0.998b-r3::gentoo  USE="ipv6 zlib" 151 KiB

Total: 3 packages (3 new), Size of downloads: 151 KiB