Question

When I using this code
reference here: http://support.microsoft.com/kb/831226

I can complier success, but when i use it doing some dns query, the return address is weird, for example: 176.20.31.0 (this shouldn’t be a valid address)

Here is my output:

C:\dnsq\Debug>dnsq.exe -n tw.media.blizzard.com -t A -s 8.8.8.8
The IP address of the host tw.media.blizzard.com is 176.20.31.0

But actually the tw.media.blizzard.com should be: (I query it by nslookup)

# nslookup tw.media.blizzard.com 8.8.8.8
Server:         8.8.8.8
Address:        8.8.8.8#53

Non-authoritative answer:
tw.media.blizzard.com   canonical name = tw.media.blizzard.com.edgesuite.net.
tw.media.blizzard.com.edgesuite.net     canonical name = a1479.g.akamai.net.
Name:   a1479.g.akamai.net
Address: 23.14.93.167
Name:   a1479.g.akamai.net
Address: 23.14.93.157

My question is why dnsquery doesn’t work on some FQDN?
Any suggestion would be appreciated 🙂

Answer 1

I found the problem.

For those FQDN which leading to invlid address, the common thing are all of their DNS record type are “DNS_TYPE_CNAME”, not DNS_TYPE_A.

So we need to parse the whole PDNS_RECORD to get DNS_TYPE_A information.

---

I’ll post my change here:

Original code from MS:

    if(wType == DNS_TYPE_A) {
        //convert the Internet network address into a string
        //in Internet standard dotted format.
        ipaddr.S_un.S_addr = (pDnsRecord->Data.A.IpAddress);
        printf("The IP address of the host %s is %s \n", pOwnerName,inet_ntoa(ipaddr));

        // Free memory allocated for DNS records. 
        DnsRecordListFree(pDnsRecord, freetype);
    }

My change here:

    if(wType == DNS_TYPE_A) {
        //convert the Internet network address into a string
        //in Internet standard dotted format.
        PDNS_RECORD cursor;

        for (cursor = pDnsRecord; cursor != NULL; cursor = cursor->pNext) {
            if (cursor->wType == DNS_TYPE_A) {
                ipaddr.S_un.S_addr = (cursor->Data.A.IpAddress);
                printf("The IP address of the host %s is %s \n", pOwnerName,inet_ntoa(ipaddr));                 
            }
        }

        // Free memory allocated for DNS records. 
        DnsRecordListFree(pDnsRecord, freetype);
    }