(1) If service on individuals as provided in Section 2-15 is not made on any respondent within a reasonable time or if it appears that any respondent resides outside the State, service may be made by certified mail. In such case the clerk shall mail the summons and a copy of the petition to that respondent by certified mail marked for delivery to addressee only. The court shall not proceed with the adjudicatory hearing until 5 days after such mailing. The regular return receipt for certified mail is sufficient proof of service.
     (2) Where a respondent’s usual place of abode is not known, a diligent inquiry shall be made to ascertain the respondent’s current and last known address. The Department of Children and Family Services shall adopt rules defining the requirements for conducting a diligent search to locate parents of minors in the custody of the Department. If, after diligent inquiry made at any time within the preceding 12 months, the usual place of abode cannot be reasonably ascertained, or if the respondent is concealing the respondent’s whereabouts to avoid service of process, petitioner’s attorney shall file an affidavit at the office of the clerk of court in which the action is pending showing that the respondent on due inquiry cannot be found or is concealing the respondent’s whereabouts so that process cannot be served. The affidavit shall state the last known address of the respondent. The affidavit shall also state what efforts were made to effectuate service. Within 3 days of receipt of the affidavit, the clerk shall issue publication service as provided below. The clerk shall also send a copy thereof by mail addressed to each respondent listed in the affidavit at the respondent’s last known address. The clerk of the court as soon as possible shall cause publication to be made once in a newspaper of general circulation in the county where the action is pending. Notice by publication is not required in any case when the person alleged to have legal custody of the minor has been served with summons personally or by certified mail, but the court may not enter any order or judgment against any person who cannot be served with process other than by publication unless notice by publication is given or unless that person appears. When a minor has been sheltered under Section 2-10 of this Act and summons has not been served personally or by certified mail within 20 days from the date of the order of court directing such shelter care, the clerk of the court shall cause publication. Notice by publication shall be substantially as follows:
     “A, B, C, D, (here giving the names of the named respondents, if any) and to All Whom It May Concern (if there is any respondent under that designation):
     Take notice that on (insert date) a petition was filed under the Juvenile Court Act of 1987 by …. in the circuit court of …. county entitled ‘In the interest of …., a minor’, and that in …. courtroom at …. on (insert date) at the hour of …., or as soon thereafter as this cause may be heard, an adjudicatory hearing will be held upon the petition to have the child declared to be a ward of the court under that Act. THE COURT HAS AUTHORITY IN THIS PROCEEDING TO TAKE FROM YOU THE CUSTODY AND GUARDIANSHIP OF THE MINOR, TO TERMINATE YOUR PARENTAL RIGHTS, AND TO APPOINT A GUARDIAN WITH POWER TO CONSENT TO ADOPTION. YOU MAY LOSE ALL PARENTAL RIGHTS TO YOUR CHILD. IF THE PETITION REQUESTS THE TERMINATION OF YOUR PARENTAL RIGHTS AND THE APPOINTMENT OF A GUARDIAN WITH POWER TO CONSENT TO ADOPTION, YOU MAY LOSE ALL PARENTAL RIGHTS TO THE CHILD. Unless you appear you will not be entitled to further written notices or publication notices of the proceedings in this case, including the filing of an amended petition or a motion to terminate parental rights.
     Now, unless you appear at the hearing and show cause against the petition, the allegations of the petition may stand admitted as against you and each of you, and an order or judgment entered.

         Dated (insert the date of publication)”
 
     (3) The clerk shall also at the time of the publication of the notice send a copy thereof by mail to each of the respondents on account of whom publication is made at each of the respondents’ last known address. The certificate of the clerk that the clerk has mailed the notice is evidence thereof. No other publication notice is required. Every respondent notified by publication under this Section must appear and answer in open court at the hearing. The court may not proceed with the adjudicatory hearing until 10 days after service by publication on any parent, guardian or legal custodian in the case of a minor described in Section 2-3 or 2-4.
     (4) If it becomes necessary to change the date set for the hearing in order to comply with Section 2-14 or with this Section, notice of the resetting of the date must be given, by certified mail or other reasonable means, to each respondent who has been served with summons personally or by certified mail.
     (5) Notice to a parent who has appeared or been served with summons personally or by certified mail, and for whom an order of default has been entered on the petition for wardship and has not been set aside shall be provided in accordance with Supreme Court Rule 11. Notice to a parent who was served by publication and for whom an order of default has been entered on the petition for wardship and has not been set aside shall be provided in accordance with this Section and Section 2-15.