Explanation/Reference:
Explanation:
http://blogs.msdn.com/b/mvpawardprogram/archive/2013/03/18/virtual-directories-exchange-2013.aspx EWS virtual directory (Exchange Web Services)
A virtual directory is used by Internet Information Services (IIS) to allow access to a web applications in Exchange 2013 Autodiscover Service, ECP, EWS, ActiveSync, OWA, OAB, Powershell are the available virtual directories through EAC.
You can manage a variety of virtual directory settings on Exchange 2013 including authentication, security, and reporting settings. I am explaining here, how you can manage the Virtual Directories through Exchange Admin Center. I have also included some example PowerShell cmdltes to show how to manage those resources:

Default settings on Virtual Directories in Exchange Server 2013
http://maybe-i-know-it.blogspot.com.au/2013/05/default-settings-on-virtual-directories.html Autodiscover
[PS] C:\Windows\system32>get-autodiscovervirtualdirectory exch01\autodiscover* | fl name, internal*, external*, *authentication
Name: Autodiscover (Default Web Site)
InternalAuthenticationMethods : {Basic, Ntlm, WindowsIntegrated, WSSecurity, OAuth} InternalUrl :
ExternalAuthenticationMethods : {Basic, Ntlm, WindowsIntegrated, WSSecurity, OAuth} ExternalUrl :
LiveIdNegotiateAuthentication : False
WSSecurityAuthentication : True
LiveIdBasicAuthentication : False
BasicAuthentication : True
DigestAuthentication : False
WindowsAuthentication : True
OAuthAuthentication : True
AdfsAuthentication : False
IIS FE: Anonymous, Basic, Windows Authentication
IIS BE: Anonymous, Windows Authentication
ECP
[PS] C:\Windows\system32>Get-ecpvirtualDirectory exch01\ecp* | fl name, internal*, external*,
*authentication
Name : ecp (Default Web Site)
InternalAuthenticationMethods : {Basic, Fba}
InternalUrl : https://exch01.contoso.com/ecp
ExternalUrl :
ExternalAuthenticationMethods : {Fba}
BasicAuthentication : True
WindowsAuthentication : False
DigestAuthentication : False
FormsAuthentication : True
LiveIdAuthentication : False
AdfsAuthentication : False
IIS FE: Anonymous, Basic
IIS BE: Anonymous, Basic
EWS
[PS] C:\Windows\system32>Get-WebServicesVirtualDirectory exch01\ews* | fl name, internal*, external*,
*authentication
Name : EWS (Default Web Site)
InternalNLBBypassUrl :
InternalAuthenticationMethods : {Ntlm, WindowsIntegrated, WSSecurity, OAuth} InternalUrl : https://exch01.contoso.com/EWS/Exchange.asmx
ExternalAuthenticationMethods : {Ntlm, WindowsIntegrated, WSSecurity, OAuth} ExternalUrl :
CertificateAuthentication :
LiveIdNegotiateAuthentication :
WSSecurityAuthentication : True
LiveIdBasicAuthentication : False
BasicAuthentication : False
DigestAuthentication : False
WindowsAuthentication : True
OAuthAuthentication : True
AdfsAuthentication : False
IIS FE: Anonymous, Basic
IIS BE: Anonymous, Basic
Microsoft-Server-ActiveSync
[PS] C:\Windows\system32>Get-activesyncvirtualDirectory exch01\microsoft* | fl name, internal*, external*,
*authentication
Name : Microsoft-Server-ActiveSync (Default Web Site)
InternalUrl : https://exch01.contoso.com/Microsoft-Server-ActiveSync
InternalAuthenticationMethods : {}
ExternalUrl :
ExternalAuthenticationMethods : {}
IIS FE: Basic
IIS FE: Basic
OAB
[PS] C:\Windows\system32>Get-oabVirtualDirectory exch01\oab* | fl name, internal*, external*,
*authentication
Name : OAB (Default Web Site)
InternalUrl : https://exch01.contoso.com/OAB
InternalAuthenticationMethods : {WindowsIntegrated}
ExternalUrl :
ExternalAuthenticationMethods : {WindowsIntegrated}
BasicAuthentication : False
WindowsAuthentication : True
IIS FE: Windows Authentication
IIS FE: Windows Authentication
OWA
[PS] C:\Windows\system32>Get-OwaVirtualDirectory exch01\owa* | fl name, internal*, external*,
*authentication Name : owa (Default Web Site)
InternalAuthenticationMethods : {Basic, Fba}
InternalUrl : https://exch01.contoso.com/owa
ExternalUrl :
ExternalAuthenticationMethods : {Fba}
BasicAuthentication : True
WindowsAuthentication : False
DigestAuthentication : False
FormsAuthentication : True
LiveIdAuthentication : False
AdfsAuthentication : False
IIS FE: Basic
IIS BE: Anonymous, Windows Authentication
PowerShell
[PS] C:\Windows\system32>Get-powershellvirtualDirectory exch01\powershell* | fl name, internal*, external*,
*authentication Name : PowerShell (Default Web Site)
InternalAuthenticationMethods : {}
InternalUrl : http://exch01.contoso.com/powershell
ExternalAuthenticationMethods : {}
ExternalUrl :
CertificateAuthentication : True
LiveIdNegotiateAuthentication : False
WSSecurityAuthentication : False
LiveIdBasicAuthentication : False
BasicAuthentication : False
DigestAuthentication : False
WindowsAuthentication : False
OAuthAuthentication : False
AdfsAuthentication : False
IIS FE: None
IIS BE: Windows Authentication
RPC
[PS] C:\>Get-outlookanywhere exch01\rpc* | fl name, internal*, external*, *authentication Name : Rpc (Default Web Site)
InternalHostname : exch01.contoso.com
InternalClientAuthenticationMethod : Ntlm
InternalClientsRequireSsl : False
ExternalHostname :
ExternalClientAuthenticationMethod : Negotiate
ExternalClientsRequireSsl : False
IIS FE: Basic, Windows Authentication
IIS FE: Windows Authentication
NOT A D
Not related to a certificate issue
NOT C
You may create a new Autodiscover site if your organization has multiple e-mail domains and each requires its own Autodiscover site and corresponding virtual directory, use the New- AutodiscoverVirtualDirectory cmdlet to
create a new Autodiscover virtual directory under a new Web site.
Not required in this scenario.
If you were going to create a new Autodiscover site then you would have to delete the old one first.
B
Need to modify the EWS virtual directory in order to create the external URL.

E
Need to modify the OAB virtual directory to create the External URL

http://technet.microsoft.com/en-us/library/bb123710(v=exchg.150).aspx
http://technet.microsoft.com/en-us/library/bb232155(v=exchg.150).aspx
http://technet.microsoft.com/en-us/library/bb125170(v=exchg.150).aspx