round robin dns's and ip addresses
Kevin Darcy
kcd at daimlerchrysler.com
Sat Aug 13 00:06:31 UTC 2005
yawnmoth wrote:
>If a particular domain is using a round robin DNS and has 2+ IP
>addresses associated with it, is there any way I could get a list of
>all the IP addresses associated with the domain? gethostbyname will
>return one IP address, but I'd like all of them...
>
>PHP has a function - gethostbynamel - that looked useful, but it, too,
>only returns one IPaddress...
>
What OS are you using? On all (Unix-like) OSes I know, gethostbyname()
returns a struct hostent, which contains a *list* of IP addresses, not
just a single address, e.g.
struct hostent {
char *h_name; /* canonical name of host */
char **h_aliases; /* alias list */
int h_addrtype; /* host address type */
int h_length; /* length of address */
char **h_addr_list; /* list of addresses */
};
Failing that, use Perl and the Net::DNS module, which makes it fairly
trivial to find all of the A records (just loop through all the "rr"
objects in the "answer" array, which is a member of the "packet" object
that was returned by your query, looking for ones with "type" set to "A").
- Kevin
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