How to resolve IP addresses into the domain name?

[PilotJLR]

I know there's a simple answer to this, but I haven't been able to find it...

Can anyone remind me how to resolve an IP address into a domain name / FQDN. In other words, something to let me know IP address 1.2.3.4 is really mydomain.com.
I know there's websites that do this, but there's also a command utility... that's what I'm looking for.

Thanks!

[William Haller]

nslookup x.x.x.x

or, as an alternative

whois x.x.x.x

[PilotJLR]

Ah ha! I tried nslookup a few times before, no luck on that. But whois works perfectly. Thank you!!

[ccrvic]

Originally Posted by PilotJLR

Can anyone remind me how to resolve an IP address into a domain name / FQDN

If there's a PTR record in DNS, use "dig -x a.b.c.d". If there isn't, you need whois to tell you about the netblock it's in...

Vic.

[ibbo]

if you have mysql installed then you should have resolveip.

Its fully backward forward I.E 192.... would give domain name while domain name will give IP.

Fiiling that compile this

#include <stdio.h>          /* stderr, stdout */
#include <netdb.h>          /* hostent struct, gethostbyname() */
#include <arpa/inet.h>      /* inet_ntoa() to format IP address */
#include <netinet/in.h>     /* in_addr structure */

int main(int argc, char **argv) {
            struct hostent *host;     /* host information */
            struct in_addr h_addr;    /* internet address */
            if (argc != 2) {
              fprintf(stderr, "USAGE: nslookup <inet_address>\n");
              exit(1);
            }
            if ((host = gethostbyname(argv[1])) == NULL) {
              fprintf(stderr, "(mini) nslookup failed on '%s'\n", argv[1]);
              exit(1);
            }
            h_addr.s_addr = *((unsigned long *) host->h_addr_list[0]);
            fprintf(stdout, "%s\n", inet_ntoa(h_addr));
            exit(0);
}

It only return the IP from the domain I.E nslookup google.com returns 72.14.207.99

Ibbo

[aleph]

dig -x [IP ADDR]