we know that every maximal ideal in $C(X)$ is in this form: $$M^p=\left\{\,f \in C^*(x):\ p\in cl_{\beta X} Z\left(f\right)\,\right\}$$ and every maximal ideal in $C^*(X)$ is $$M^{*p}=\left\{\,f\in C^*(X):\ f^{\beta}\left(p\right)=0\,\right\}$$ and it is not necessary that $$ M^p \cap C^*(X) = M^{*p}$$ My question is: If are prime ideals of $C(X)$ contained in $M^p$, in a one to one corresponding to that of $C^*(X)$ contained in $M^{*p}$ for $p\in \beta X$ ? ---------------------- $M^p$ and $M^{*p}$ are maximal ideals respectively in $C(X)$ and $C^*(X)$ correspond to $p$. $\beta X$ is Ston-cech compactification of the space $X$ for terminalogy and notions you can refer to [here][1]. [1]:https://books.google.com/books?hl=en&lr=&id=3j3SBwAAQBAJ&oi=fnd&pg=PA1&dq=Rings+of+continuous+functions&ots=0UmBXt62ta&sig=yhl_h8zAq9FKOJBIxZ1-1UgEyTc#