<PAGE>


                                                                   EXHIBIT 31.2

CERTIFICATIONS

I, Robert M. Dennerlein, certify that:


1. I have reviewed this quarterly report on Form 10-Q of Globix Corporation
for the period ended June 30, 2003;

2. Based on my knowledge, this report does not contain any untrue statement of
a material fact or omit to state a material fact necessary to make the
statements made, in light of the circumstances under which such statements were
made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations and cash flows of the registrant as
of, and for, the periods presented in this report;

4. The registrant's other certifying officer(s) and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and15d-15(e)) for the registrant and have:

            (a)  Designed such disclosure controls and procedures, or caused
                 such disclosure controls and procedures to be designed under
                 our supervision, to ensure that material information relating
                 to the registrant, including its consolidated subsidiaries,
                 is made known to us by others within those entities,
                 particularly during the period in which this report is being
                 prepared;

            (b)  Evaluated the effectiveness of the registrant's disclosure
                 controls and procedures and presented in this report our
                 conclusions about the effectiveness of the disclosure controls
                 and procedures, as of the end of the period covered by this
                 report based on such evaluation; and

            (c)  Disclosed in this report any change in the registrant's
                 internal control over financial reporting that occurred during
                 the registrant's most recent fiscal quarter (the registrant's
                 fourth fiscal quarter in the case of an annual report) that has
                 materially affected, or is reasonably likely to materially
                 affect, the registrant's internal control over financial
                 reporting; and

5. The registrant's other certifying officer(s) and I have disclosed, based on
our most recent evaluation of internal control over financial reporting, to
the registrant's auditors and the audit committee of registrant's board of
directors (or persons performing the equivalent functions):

            (a)  All significant deficiencies and material weaknesses in the
                 design or operation of internal control over financial
                 reporting which are reasonably likely to adversely affect the
                 registrant's ability to record, process, summarize and report
                 financial information; and

            (b)  Any fraud, whether or not material, that involves management
                 or other employees who have a significant role in the
                 registrant's internal controls over financial reporting.

Date: August 20, 2003
                                              GLOBIX CORPORATION

                                     /s/ Robert M. Dennerlein
                                     ------------------------------------------
                                     Name: Robert M. Dennerlein
                                     Title: Chief Financial Officer