6 reported that only one of the 400 Comcast subscribers AF Holdings identified appeared to live in the District. And Cox, AT&T, and Bright House each stated that they had no subscribers at all in the District of Columbia; indeed, they do not even offer service here. The providers also argued that any burden was necessarily undue because AF Holdings had failed to provide any reason to think that joinder of these 1,058 defendants in one action was proper. The district court rejected these arguments, holding that “considerations of personal jurisdiction and joinder are premature when discovery is sought before the plaintiff has named a defendant and the discovery is targeted to identify unknown individuals associated with the IP addresses.” But acknowledging that several other district courts had reached contrary conclusions in similar situations, and recognizing that a substantial ground for difference of opinion existed, the district court certified its order for immediate appeal. See 28 U.S.C. § 1292(b). The providers now reiterate the arguments they made in the district court—that the subpoenas are unduly burdensome because venue is improper, personal jurisdiction over these Doe defendants is lacking, and the defendants could not properly be joined together in one action. Our review is for abuse of discretion. See Recording Industry Ass’n of America, Inc. v. Verizon Internet Services, 351 F.3d 1229, Cir. 2003). discretion As when a “district it makes an court error by definition of law,” the 1233 (D.C. abuses its “abuse-of- discretion standard includes review to determine that the discretion was not guided by erroneous legal conclusions.” Koon v. United States, 518 U.S. 81, 100 (1996).