You have a hosted Exchange organization. All servers in the organization have Exchange Server 2010 Service Pack 1 (SP1) installed.
Select the proper DNS record to create when you deploy federated delegation. (Choose all that apply).
A.
A record.
B.
MX (mail exchange record).
C.
MG (mail group record).
D.
TXT record.
Explanation:
Create a TXT record for federated delegation.
The A record should actually be a CNAME, according to Technet. However, in the strictest sense, an A record would need to have been created in DNS to map the IP to the external server name, then the CNAME record would be created so the federated partner can access your network. For example:A record maps server IP to company name (i.e., 64.4.6.100 to contoso.com).
CNAME sets next record for discovery (i.e., autodiscover.contoso.com).It is unlikely that your exam will give you the option of an A record, but if there is no mention of a CNAME go with A and TXT. Otherwise, always go with CNAME and TXT.
Reference:
http://technet.microsoft.com/en-us/library/ff601760.aspx