The experts above rightly advised you that notice unaccompanied with petition is not a proper service, only in theory. Practically several courts serve the notices without annexing the petitions. Once the respondent appears in the court and informs the presiding judge about non-service of petition, the judge directs the petitioner to serve a copy of the petition there and then. This is happening even after amendment of C.P.C.
He must have mentioned in one of the paragraphs of his petition, that the parties resided together in Ludhiana and so the court in Ludhiana has got jurisdiction. It may be a blatant lie. But to prove it a lie, evidence is required. So, the court cannot through the petition on the ground of lack of territorial jurisdiction, just by your mentioning the fact that the marriage was solemnized in Delhi and the couple lived together in Delhi and the respondent is living in Delhi. Certainly, you can take up this issue as a "preliminary objection" in your reply and also if advised so, you can also move separate application requesting the court to decide the question of territorial jurisdiction.
It is important to note that in matrimonial matters, it is mandatory to the court to insist first for "mediation/counselling". So, once you appear in the court, the court will not direct you to file reply but insist you to go through "mediation/counselling". Needless to say, on the first date of hearing itself, without submitting to the jurisdiction of the court, you can ask for interim maintenance as well as lititgation expenses, if you are in need of those things.
Finally, I suggest you, the proper course of action for you is to consult an advocate and file appropriate case against your husband in Delhi jurisdiction and fle transfer petition in S.C. seeking transfer of his case from Ludhiana to Delhi.
