Hi All

[Jim Reid]

>>>>> "Servet" == Servet Zeybek <zeybek at mustang.europe.nokia.com> writes:

    Servet> 1 - MG (Mail Group Member): In RFC it says: " A
    Servet> <domain-name> which specifies a mailbox which is a member
    Servet> of the mail group specified by the domain name" lets say,
    Servet> I have the name "example.com" to lookup with this type of
    Servet> query(MG), does example.com specify a group? what does
    Servet> this query exactly mean? what should the answer be? When i
    Servet> try to look up the address (www.hotmail.com) i get a SOA
    Servet> answer, the address(www.google.com) i get a CNAME
    Servet> answer. Here i got confused, why 2 different answers, and
    Servet> why SOA and CNAME!!

You didn't get different answers. They both said the same thing. But
the name servers said it in different ways: there's no MG record for
www.google.com or www.hotmail.com. This should come as no surprise as
MG records have been deprecated and nobody has used them for years.
Read RFC2308's sections on negative responses if you want to know more.

    Servet> 2- MR (Mail rename domain name): RFC says; "A
    Servet> <domain-name> which specifies a mailbox which is the
    Servet> proper rename of the specified mailbox". Does that mean;
    Servet> the name (example.com) is assigned a mailbox(MB request),
    Servet> and MR gives an alternative mailbox for example.com? When
    Servet> i try this MR query with (www.google.com) i get a CNAME
    Servet> answer!!! isnt this illogical?

See above. MR records have been dead and buried for as long as MG
records. 

    Servet> 3- NULL : What is the purpose of this request? When i try
    Servet> this with www.google.com, i get a CNAME answer and with
    Servet> www.hotmail.com i get a SOA answer!!

See above. This time the two name servers are saying there's no NULL
record -- yet another less than useless record type -- for
www.google.com or www.hotmail.com.

The reason you probably always get a CNAME back for any record type
when looking up www.google.com is simple. The folk at Google pretty
much want to ensure that very lookup for www.google.com gets given an
answer that will point the client at their web server. The returned
CNAME does that.

    Servet> 4- PTR(Domain name Pointer): how different is this from
    Servet> CNAME?

In simple terms PTR records are for reverse mapping IP addresses to
hostnames. CNAMEs are a way of aliasing one domain name to another.

    Servet> 5- what is "additional section processing"? 

Just what it says. It documents how name servers and resolvers are
expected to process any data in the Additional Section of a reply.

Here are some exclamation marks as you seem to like them: !!!!! :-)