Determine whether this relation is reflexive, symmetric, antisymmetric and/or transitive?

Question

R is defined on $\mathbb{N} × \mathbb{N}$ by $(a, b)R(c, d)$ iff $a \leq c$ and $b \leq d$.

I think it's reflexive and transitive. Not too sure about it being symmetric or antisymmetric.

Any help would be appreciated!