Logjam determines if a site is vulnerable

Another TLS attack was recently posted: Logjam . The problem has a really clear description and demonstrates that sites using a key size of 512 are vulgar and it takes up to 10 minutes to "decrypt client server key keys".

Based on the nature of the attack, it is clear that clients and servers must be vulnerable to this type of attack. It seems that only recent browsers have implemented security fixes to mitigate this vulnerability. Hovewer, if you work with "widely used" web applications and also have to support IE 8, 9+, in other browsers it is unlikely that most users will have client side security patches.

And it is interesting to know if the server is vulnerable or not if the key size is 1024 bits. Based on the description of Logjam, this is only a recommendation / recommendation: "it is preferable to have a key of 2048 bits". This online test contains the following information:

Attention! This site uses the widespread 1024-bit Diffie-Hellman group, and may be within the nation-state divide. It might be a good idea to create a unique 2048-bit group for your site.

Does this mean that the site is potentially vulnerable?