hi,

see admission to abroad university is based on exam score in IELTS, TOEFEL  like test and also depends on the overall academic records, projects, extra curricular activities , letter of recommendation etc. however there may be institutional priority to tier 1 institute. delhi university is one of the best university In india , so it might chances that students of du may get some advantage for it. but it is not impossible for students of others university to crack a tier 1 abroad college. so dont tension about it, just study sincerely towards your goal and clear all the exams which are left with excellent score.