For a person who is considered a traveler by the Shariah, it is necessary to offer Salaat as “Qasar” i.e. offer 2 Raka\'at of Fardh Salaat instead of the usual 4 Raka\'at.
The Salaat should be made up (i.e. Qaza) in the same order in which it was missed, whether it was missed in a journey or in the home country. Thus, when you were in a journey and you missed Salaat there, you have to offer the Qasar Salaat (i.e. 2 instead of 4) only as Qaza and not the full Salaat.
And Allah Most High knows best.
Mufti Syed Ziauddin Naqshbandi Qadri
[Professor, Islamic Law, Jamia Nizamia,
Founder-Director, Abul Hasanaat Islamic Research Center]