Determing if a domain is a subdomain in PHP

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Posted by GregVernon, 01-13-2010, 12:13 AM
Hey everyone, I'm trying to filter out particular "free" domains, namely co.cc, from being allowed into the HostLaunch review database. I know I could manually set filters, but I'm curious is there is native way in PHP to determine if a domain is really a subdomain (such as *.co.cc) or an actual domain.
Posted by Jamza, 01-13-2010, 12:36 AM
I'm not sure what you mean by native, if you mean as in a function. I don't think there is one sorry. You could always do a whois lookup on a domain, if it returns registrant information and nameservers etc It is a subdomain. Co.cc returns this. Whereas a whois lookup on Co.uk returns no domain information as it is a TLD and not technically registered to anyone.
Posted by GregVernon, 01-13-2010, 01:00 AM
Yeah, I was thinking that. I'm concerned about resource usage, though. I'm using a shared host at the moment, so even when I store a valid or invalid result for each tld, it will take up resources I don't necessarily want to take up. I think for now I'll just need to ban fake tld's in the software.
Posted by bigfan, 01-13-2010, 09:51 AM
No, co.uk is a second-level domain; uk is the TLD, delegated to and administered by Nominet UK. It allows registration of third-level domains only, under co.uk, gov.uk, org.uk, etc.
Posted by Killer Tofu, 01-13-2010, 03:24 PM
You can check the number of .'s in the string (referring URL or submitted url) -- that can help you decide, right? Aka if you say give us the direct URL to your site, it should be like google.com that's 1 period if they give you apps.google.com that's 2 periods
Posted by tech163, 01-13-2010, 07:44 PM
Try this script:
Posted by Negizmo, 01-13-2010, 09:11 PM
Think. google.co.uk That's two dots, but it's certainly not a subdomain - that logic is majorly flawed. You may be better off just manually banning.
Posted by GregVernon, 01-14-2010, 03:35 AM
My thoughts exactly.

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