gethostbyaddr

Anon

Hallo, my problem:
How can I get the domain names of the IPs that return an error in the function (host gethostbyaddr(ip))?
Please Help.

Thanx

rrijnders

Return what error?

Anon

When it returns the same IP that was called in the function gethostbyaddr(ip).On error this function does not retrurn the host name but the ip.

I don't know how to get the host names of these IPs.

Anon

Not all IPs have hostnames attached with them.

Diego

rrijnders

First of all, understand that not all IP's are associated with host names. Host names are a function of DomainNameServices. They are a convenience, not a requirement of the IP protocol. It is perfectly legitimate to get an assigned IP and then put up a web page without a domain. People can then access that page directly by using the IP (ex http://192.148.20.101/).

Even if the IP does have a domain associated with it, your ability to determine that domain is dependent upon your DNS server and all the DNS servers along the path to the IP having Reverse DNS entries in their databases. This, also, is not a requirement.

In short (too late) you may not be able to get a domain for an IP for a host (no pun intended) of reasons.

The best you could do is to search the Internic registry to find out to whom a class (block) of IP's is reserved for. Even this is sometimes not helpful. One company may have reserved a big class A block and then sub-leased lower class B, C, or single IP's to other company's or users.

I know this is not an answer to your problem, but it is an explaination.

HTH
-- Rich