I'm hosting a website on my server, but the customer wants to manage their own mail server. So they provided me with an IP address. So I tried to change the mx entry through Cpanel to that IP address. It did not work. Later I found out that I would need to have a name rather than IP. But how do I do that?
Also, I've read you can change the mx entry using the original registrar like NetworkSolutions using advanced DNS entry. The question is where do I change it: in CPanel or using the NetworkSolutions advanced DNS ?
When making DNS changes you can always use the "dig" command line tool (part of the BIND package) to query a nameserver directly. This will ensure that you are not seeing the results of caching and so there is no propagation delay.
So if your nameserver is ns1.mydomain.com, and your client's domain (the one you're switching mx entry for) is clientdomain.com, type the following in the Linux shell:
dig @ns1.mydomain.com clientdomain.com mx
This means you want to look up the "mx" type record (must be lowercase). You should get a reply that looks something like this:
;; QUESTION SECTION:
;clientdomain.com. IN MX
;; ANSWER SECTION:
clientdomain.com. 86400 IN MX 10 smtp.clientdomain.com.
;; AUTHORITY SECTION:
clientdomain.com. 86400 IN NS ns1.mydomain.com.
;; ADDITIONAL SECTION:
smtp.clientdomain.com. 86400 IN A 18.104.22.168
ns1.thetahost.com. 86400 IN A 22.214.171.124
The "QUESTION SECTION" simply indicates the query you were making. You want to know the MX record for clientdomain.com.
The "ANSWER SECTION" is the answer to your query. The DNS server has replied that smtp.clientdomain.com is the MX host for that domain. The "10" (may be some other number) is the priority for that MX server (since there can be more than one for redundancy).
The "AUTHORITY SECTION" means that ns1.mydomain.com is indicating that it is the authority for that domain and not simply relaying that information from somewhere else.
The "ADDITIONAL SECTION" provides IP addresses for the hosts in the other sections. Here you can see that smtp.clientdomain.com has an IP address of 126.96.36.199.
If you don't get a result back from the dig request (in which case the QUESTION section is there but not the others), or your results don't match, there is still something wrong with your config.