DNS / Email urgent Help Please

Hi Guy,
I changed my DNS provider/records from Memset to 123-reg - this was done on 17/3/2015 2days ago.. I am finding that over 3G/4G connection (iPhone 02 / dongle) and some other LAN connections I can not even ping the A records it is very intermittent  I get "ping request could not find host.... please check name try again"- soon as I switch to WIFI it all works fine.. example of one my A record is mail.mydomain.co.uk.. everything internally works a treat..it was all working fine only until I switched over DNS provider...the DNS records are all setup fine... Has anyone got any ideas what might be causing this?
jag bAsked:
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Zephyr ICTCloud ArchitectCommented:
What was the ttl set on the DNS records with the old provider? Maybe the old provider is still in cache at some public DNS servers which might cause intermittent results...
Benjamin MOREAUProject ManagerCommented:
First, you can check if all DNS config is OK or not :

jag bAuthor Commented:
my domain is "abmcatering.co.uk" I have 3 A records mail/mobile/remote which point to my real IP....  MX records are all fine... I can ping the actual IP no issues... I on a PC that has a LAN connection at a school - I cant even ping the IP address of real IP or the A record...
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Zephyr ICTCloud ArchitectCommented:
mail.abmcatering.co.uk has a total other ip-address than your A-record, is this normal, it might be, since your mail is hosted.
Just checking ... I do see that indeed not all DNS servers have the new records yet ... At least that is my initial thought/check
jag bAuthor Commented:
my real IP is: (this has my x3 A records) / and my web-hosting is: ( I have setup x2 A records with "www" and "@" for this IP) I have no other A records or CNAME records in my DNS. My email is hosted with  hosted email security with 3rd party....
Do you think everything from my end is ok?
Neadom TuckerCommented:
Yes it all looks fine.  Looking on http://centralops.net/ all your dns names resolve to the correct address.  Depending on the wireless carrier they may be blocking or not allowing or limiting ICMP (Ping).  

I get no dropped packets from here in good old Charleston, South Carolina, USA.

I think you should be good.
jag bAuthor Commented:
could certain networks take more time to register these DNS changes??
Zephyr ICTCloud ArchitectCommented:
Yes, it can take upto maybe 72 hours or more before all public DNS servers get the new records, and if the previous TTL was high enough it can sometimes take even longer.
Neadom TuckerCommented:
Yes and No.  It all depends on what your TTLs are set to.  Yours are set to 4 hours.  So every 4 hours other dns servers get an updated DNS entry when it is queried and does not go by it cache and holds it for another 4 hours or until the DNS cache is flushed.

The test is to ping the domain name from several other locations and see what folks are seeing.  Its been 72 hours so I imaging all the records are updated.  the only reason this would be an issue is if someone had a STATIC DNS or Host Entry.  This would then need to be edited manually.

Is it still not working?
jag bAuthor Commented:
Guys - an update - think this is the issue.. basically as Godaddy is hosting my website abmcatering.co.uk - they also have records with Mail / autodiscover - and MX records.. I changed the MX records to my server and it works fine... I deleted the autodiscover record from godaddy and works now.... can I remove all these MX records and mail records from here as I am using 123-reg to manage my DNS??
Neadom TuckerCommented:
You only need one mx record and it is ONLY for inbound mail.  So the Mail servers know where to point mail to.  MX records go in priority from least to greatest.  As far as mail.domain.com. This is something for you to decide. Do you use that domain entry for anything?  If not then get rid of it.
jag bAuthor Commented:
basically I used 123-reg for all my domain DNS records (MX / mail / A records) / godaddy is ONLY for webhosting - but this had records such as mail and mx record details - im guessing all these records can be deleted ? except the web hosting records...
Just to be sure that you will not run into issues with godaddy delete the mx and related A records, then add them back so that they are the same as with 123-reg. This is to prevent sources within the godaddy network from not getting the information when trying to reach your mailservers.

With regards to theory;

You can have multiple MX records, all MX records have a routecost associated with them. Often 10 and 20 are used, as the word cost implies the lowest value will be used (cheapest) and the higher value will only be used if the lower value can't be reached (unless explicitly defined by the sending server to use the reverse order; a tactic used by spammers.

MX records can point to either an A record or a CNAME record, most implementations will accept IP addresses but that will give issues as the ip address is assumed to be an A record in such a case. According to the RFC only A or CNAME records should be used.
jag bAuthor Commented:
Thanks for the reply - I was thinking to delete all the MX and A records from GoDaddy and just keep the Web-Hosting records that are required... as 123-Reg is managing all my DNS records...this would be ok right?
I wouldn't do that, as you have no way of knowing which servers are using the godaddy nameservers (most likely all their internal servers are using the same nameservers), it could result in your domain being unable to receive mail from anybody using godaddy including your own website (if you use a mailform of sorts).

My advice:
1. delete all MX and A records related to your mail config in the godaddy nameservers
2. recreate all MX and A records related to your mail config in the godaddy nameservers so that they match those in 123-reg.

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