How to take backup/restore of MBR with dd command?

The MBR is located in the first 512 bytes of the disk (the first sector).

Size (bytes) Description
446 Executable code section
4 Optional Disk signature
2 Usually nulls
64 Partition table
2 MBR signature

1. backup : execute following command

dd if=/dev/hda of=/mbrbackup.bin bs=512 count=1

2. Restore :

dd if=/mbrbackup.bin of=/dev/hda bs=512 count=1

Try it now :)