I get this when I analyze my mail domain on mxtoolbox ... SOA Serial Number Format is Invalid SOA Expire Value out of recommended range (Ubuntu 16.04.1 LTS (Xenial Xerus)) ISPConfig 3.1.2 please can you go me some pointers to fix this ? thanks
ISPConfig sets a expire time of 7 days. MXToolbox suggests to use a value of 1 - 2 weeks, which I wont use on my servers. It is up to you which value you set, you can configure it in the zone settings. the value is always in seconds. Regarding Serial number format, which exact serial number do they complain on?
the format info is as follows :- Filter This About DNS SOA Serial Number Format The serial number is an unsigned 32 bit value assigned to your SOA record must be between 1 and 4294967295. We will issue a warning if your serial is either invalid by being outside of the allowed range or if it does not conform to this format. Additional Information It has become common to set your serial number with a date format to make it easier to to manage. This format uses 10 digits to represent the date and then a two digit sequence number with the format of YYYYmmddss.
I just created a DNS zone in ISPConfig and the serial that was generated is perfectly fine: 2018040201 it uses the recommended date format and is in the 32bit value range. Maybe you use some kind of third party plugin or extension that sets a wrong soa value in ISPConfig? Edit a value in the zine, e.g. increase the ttl by one and save, then wait a few minutes and check the serial again.
