[Frank Grimes]

Is it okay to use dns_get_record to validate a url? That is, just to prove it exists if someone uses it in an email address or gives a link?

[ManiacDan]

It's easier just to send an activation email to the account. Hotmail exists. sicunwe4cn2487vno48vn4@hotmail.com doesn't.

[Frank Grimes]

In this case I'd only look for hotmail.com and truncate anything before the @.

Just looking for ways to sniff out asldjfassdflj.com kind of addresses.

[ManiacDan]

Why are you trying to sniff those out? If I can't make dan@sdcunwecwncvwjn.com, I'll just make dan-sdcunwecwncvwjn@hotmail.com

[Frank Grimes]

I'm not just looking for email addresses. I also need to find fake urls. This is for the forms on a site when people are asked to provide links to their facebook, twitter or other sites.

I want to trap bots and others from trying to enter asldjflajf.com as their facebook page.

I know PHP has a lot of functions for this, but I really like the info I get from this function vs checkdnsrr or something.

[requinix]

Stupid bots you can filter out but, as pointed out, it's absolutely trivial to get around this.

First I'd do some research into what all qualifies you to receive mail. An MX record, obviously, but that's not required: I assume A, AAAA, and CNAME all work too, but are there others? Then dns_get_record for everything and make sure there's at least one of those records in the list returned.

[ManiacDan]

I want to trap bots and others from trying to enter asldjflajf.com as their facebook page.

But what I'm saying is: You're going to do all this work just so that bot authors have to put www.facebook.com/asldjflajf instead of asldjflajf.com. The URL is still fake. You're wasting your effort. A captcha is ten times more effective (and ten times easier) than trying to do real-time validation of cname records.

[E-Oreo]

Is it okay to use dns_get_record to validate a url? That is, just to prove it exists if someone uses it in an email address or gives a link?

Is it OK? Sure, but just keep in mind what the result actually means: it means that the domain is registered and DNS records exist for the host name. It doesn't mean the URL is syntactically valid, it doesn't mean any resource is hosted at that URL, it doesn't mean a web server is running on the host, it doesn't mean an email account is valid, and it doesn't mean a mail server is running on the host. So if your goal is to check whether DNS records exist for the host then it will accomplish what you want.

However, I agree that it's not worth the effort.