Physical address of Page Table Entries

Hi all, *Question: * When we use 2 level paging(Directory+Table+Offset), does the page table entries have to be put exactly on the beginning of a page frame? *Description: * The format of Page Directory and Page Table are the same. And they all contain 20 bits as a pointer to the next level entries. For Page Table entry, I understand that 20 bits is enough because page frames are 4k aligned. But for Page Directory entry, the 20 bits should be the address of a Page Table, that means the physical address of a Page Table entry should be 4k aligned too. And thus they may only exist at the beginning of a page frame. Is this right or am I missing something? Thanks.