| Host id | Parent_id | Name |
|---------|-----------|------|
|    1    |  (null)   |  A   |
|    2    |  (null)   |  B   |
|    3    |  (null)   |  C   |
|    4    |     1     |  D   |
|    5    |     4     |  E   |
|    6    |     5     |  F   |

| Host id | Name |
|---------|------|
|    1    |  A   |
|    2    |  B   |
|    3    |  C   |
|    4    |  AD  |
|    5    |  ADE |
|    6    |  BF  |