What advertising network is this?
Depending on how terminal savvy you are.. you might look into sleuthing around using lsof and netstat. 

This will only work with a jailbroken iOS device. Install the packages network-cmds and lsof using Cydia. 

Close all your other applications, except for the one generating the ad. Then, open a Terminal, run one of these commands and look through the list. Simply use the process of elimination to figure out which IP address it is talking to. (IE: if you know you are running Spotify for music, you could rule out any active connections that are going to a website with "spotify" in the hostname.) After narrowing it down, if you are left with a set of IP addresses instead of hostnames, you could try running the remaining ones through an IP address lookup webpage.

Here are the commands. I've supplied a little bit of sample output from my mac to show you what I get. These are the same commands in the packages above for iOS, so you should get equivalent output. Be warned, you will get a lot of output, so be prepared to scroll.

[MacBook-Pro:~] jonathan% lsof -i

COMMAND    PID              USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
UserEvent  228 jonathan    6u  IPv4 &lt;MAC&gt;      0t0  UDP *:*
Mail       240 jonathan   34u  IPv4 &lt;MAC&gt;      0t0  TCP 192.168.1.124:49590-&gt;17.158.8.25:imaps (ESTABLISHED)
Mail       240 jonathan   37u  IPv4 &lt;MAC&gt;      0t0  TCP 192.168.1.124:49533-&gt;17.158.8.25:imaps (ESTABLISHED)


OR try

[MacBook-Pro:~] jonathan % sudo netstat
Active Internet connections  
Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)
tcp4       0      0  192.168.1.124.50428    cache.google.com.https ESTABLISHED
tcp4       0      0  192.168.1.124.50427    cache.google.com.https ESTABLISHED


Where 192.168.1.124 will be your local IP address instead of what is shown above.