For arp, pass the -n switch:

# arp -an

I don't see any dns activity with ftp if numeric addresses are used.
If a hostname is used, dns is required to resolve it to a numeric
address.

You can change timeout parameters in resolv.conf:

options timeout:x attempts:y

Or from code:

# include <resolv.h>

struct  __res_state * res = __res_get_state();

res->retrans = x;
res->retry = y;

getaddrinfo(...);

On Wed, Jan 07, 2015 at 01:48:14PM +0530, Sajal Malhotra wrote:
> Hi Nick,
> 
> Thanks for your Reply.
> It seems in QNX we can configure multiple logical IP Addresses in Same Subnet
> on a particular ethernet interface.
> Now since this is not blocked by OS, we want to somehow control which IP
> Address the OS uses as Source IP while generating DNS Traffic. Is this possible
> somehow?
> 
> Further needed help on another related topic: 
> While we configured the DNS Server IP in resolv.conf:
> - We were observing that on calling "gethostbyname()" API, OS was generating
> DNS Request and on not getting any reply it was making re-attempts (6 times or
> so) before returning failure. 
> - If 2 DNS Server IPs are configured in resolv.conf then we observe that the
> delay between subsequent attempts further increases with period of each attempt
> also increasing incremently.
> - Also we observed that when resolv.conf is in use, then on executing "arp -a"
> or doing FTP, we see that OS Starts generating DNS Traffic for each IP in ARP
> Table and there is a delay in output.
> 
> Queries:
> - In Linux we know it is possible to control the number of attempts and
> interval between each attempt by configuring parameters in resolv.conf. Is the
> same also possible in QNX?
> - How can we stop generation of DNS Traffic on execution of commands like "arp
> -a" or ftp?
> 
> Would really appreciate if you can provide some pointers for these queries.
> 
> Thanks and Regards
> Sajal
> 
> BR
> Sajal
> 
> On Mon, Jan 5, 2015 at 8:30 PM, Nick Reilly <community-noreply@qnx.com> wrote:
> 
>     Hi Sajal,
>     The DNS request will be sent to the servers specified in /etc/resolv.conf
>     and the source address used will be the one that best routes to that
>     address. As there cannot be multiple addresses in the same subnet, one
>     address will always be chosen to access a particular DNS server.
> 
>     Can you explain in a bit more detail the issue that you are facing?
> 
>     Regards,
>     Nick.
> 
> 
> 
> 
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