Even though Namecoins can be mined independently, they are usually mined as part of bitcoin mining by utilizing the merged mining technique as explained earlier. This way Namecoin can be mined as a by-product of bitcoin mining. Solo mining is no longer profitable as is evident from the following difficulty graph; instead, it is recommended to use merged mining, use a mining pool, or even use a cryptocurrency exchange to buy Namecoin.
Namecoin difficulty as shown at: https://bitinfocharts.com/comparison/difficulty-nmc.html (since December, 2016)
Various mining pools such as https://slushpool.com also offer the option of merged ...
