With other non-active domains I've had "pointed" to a hosted domain that harbors an actual website - either overlayed by the hosting company in its nameservers, or by the registrar in its nameservers - a reverse IP lookup will show the IP of the hosted domain target that the non-active domain is pointing to.
Thus, on one unique IP, reverse lookup shows the branded example.com domain and also the spare example.net variant I secured, just the two domains, as it should be.
With Godaddy, reverse IP shows my pointed domain is on their IP (220.127.116.11), shared with over a million and a half other domains.
I suppose I'm not really concerned about any SE problems, given the sheer volume of domains on this one IP. I just don't quite like the idea, and I know another registrar (bulk) does it differently.
Mostly I'm dropping this info here for the record, but does anybody know any disadvantage that could result from this?
I guess that the fact that you are pointing the domain to another that you are not expecting any SE traffic but to be on the safe side anyway i would use a free dns service such as mydomain.com for your nameservers and use them to point your domain to the other.
cabbie thanks for the suggestion - I was mostly playing around with the second domain I had, you have to park it somewhere, and I thought I'd try out godaddy's dns management.
You're right, I wasn't looking for any benefit out of it, until I checked the mydomain page it hadn't occurred to me to use a spare domain name actually as an asset, with a title and keywords, but I see I'm just out of date with modern practices(!)...I suppose that's why reverse IP has become so significant lately.
I'll try mydomain's redirection and see what a reverse IP lookup shows for that. I'll drop the info back into this thread eventually.