What kind of information about your e-mail environment is not stored in DNS?

What kind of information about your e-mail environment is not stored in DNS?

• Certificate expiration date
• SPF record
• DKIM selector
• MX 

 

EXPLANATION

Autodiscover records, MX records and DKIM selectors are provided in de public DNS zone for each domain. The expiration date for a certificate is displayed on the certificate itself.

SOURCE

https://nl.wikipedia.org/wiki/Domain_Name_System

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What is the purpose of an Exchange Autodiscover?

What is the purpose of an Exchange Autodiscover?

• It is the Microsoft version of an MX record, which tells the interwebs where mail goes and stuff...
• To pool then auto populate mail info into outlook.
• allow exchange OWA to allow users easier login.
• to establish initial connections to Exchange user mailboxes. 

EXPLANATION

Exchange Autodiscover is a web service that helps Microsoft Exchange administrators configure user profile settings for clients running Outlook 2007, Outlook 2010, or Outlook 2013 and mobile phones running Windows Mobile 6.1 or later.
Introduced in Exchange Server 2007, the primary purpose of the Exchange Autodiscover service is to establish initial connections to Exchange user mailboxes. Once

SOURCE

https://searchwindowsserver.techtarget.com/definition/Exchange-Autodiscover-service

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What port does SMTP traffic use by default?

What port does SMTP traffic use by default?

25

21

443

80 

EXPLANATION

SMTP (Simple Mail Transfer Protocol) traffic flows across TCP port 25. Some ISPs block end users from sending via this port in an effort to reduce spam and it seems to be working.
 

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One of your users can receive mail but can't send any. You notice that the "Type of Outgoing Mail Server" field is blank in the mail application. Which of the following protocols will you most likely enter as a value in this field?

One of your users can receive mail but can't send any. You notice that the "Type of Outgoing Mail Server" field is blank in the mail application. Which of the following protocols will you most likely enter as a value in this field?

• IMAP
• POP3
• NMP
• SMTP

EXPLANATION

 

POP In computing, the Post Office Protocol is an application-layer Internet standard protocol used by e-mail clients to retrieve e-mail from a server in an Internet Protocol network. POP version 3 is the most recent level of development in common use. POP has largely been superseded by the Internet Message Access Protocol.

 

IMAP In computing, the Internet Message Access Protocol is an Internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection. IMAP is defined by RFC 3501.

  SMTP is used to send email and is a protocol within the TCP/IP protocol suite. POP3 and IMAP are email retrieval protocols, not protocols for sending email.

 

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What port is recommended for secure SMTP communications between client and mailserver.

What port is recommended for secure SMTP communications between client and mailserver.

• 587
• 965
• 465
• 25 

 

EXPLANATION

Port 465 was never recognized by the IETF (Internet Engineering Task Force), as an official port for SMTP and has been assigned to another service.
Port 25 can be used but alot of ISP's block this due to the prevalence of unsecured mail servers on this port and the spam sending capabilities this exposes. Port 965 is your POP3 (receive) port, so while it is the correct POP3 port it shouldn't be used for SMTP (send).

SOURCE

https://www.jscape.com/blog/smtp-ports

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Which of the following is NOT a daemon in Postfix?

Which of the following is NOT a daemon in Postfix?

• qmgr
• master
•  crond
• smtpd 

 

EXPLANATION

The crond daemon is a Linux daemon, not a Postfix daemon.
The master daemon is the brain of the Postfix mail system. It spawns all other daemons. The smtpd daemon (server) handles incoming connections. The qmgr daemon is the heart of the Postfix mail system. It processes and controls all messages in the mail queues.

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Which provides a method for validating source of a message through cryptographic authentication ?

Which provides a method for validating source of a message through cryptographic authentication ?

• DNS
• SPF
• DNSSEC
• DKIM

EXPLANATION

DKIM provides a method for validating a domain name identity that is associated with a message through cryptographic authentication.

SOURCE

http://www.dkim.org/

 

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What is the default port used by Postfix?

What is the default port used by Postfix?

• 25
• 45
• 37
• 20 

 

EXPLANATION

Postfix is an open source mail transfer agent (MTA) that is used to route and deliver emails. Postfix is the alternate of widely
used Sendmail MTA. Postfix uses port number 25 (SMTP) by default.

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Which of these is an valid email address?

Which of these is an valid email address?

• All of them
• Michael.Scarn@[117.42.15.92]
• "dogs@r.com"@catsrule.com
• Security+@comptia.org 

 

EXPLANATION

Based on RFC 5322,
email address can have two "@" symbols as long as the first one is in quotation marks to identify the local name versus the domain name.  IP addresses can be used to identify the domain name.  The "+" symbol is valid in local names.

SOURCE

https://tools.ietf.org/html/rfc5322

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What type of DNS record is used by the Sender Policy Framework (SPF)?

What type of DNS record is used by the Sender Policy Framework (SPF)?

• TXT
• MX
• A
• CNAME 

 

EXPLANATION

Sender Policy Framework (SPF) is a simple email-validation system designed to detect email spoofing. The SPF is an open standard specifying a technical method to prevent sender-address forgery. SPF allows administrators to specify which hosts are allowed to send mail on behalf of a given domain by creating a specific SPF record (or TXT record) in the Domain Name System (DNS). Mail exchangers use DNS records to check that mail from a given domain is being sent by a host sanctioned by that domain's administrators.

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A user can receive email but cannot send any. Which protocol, responsible for sending email, is potentially not configured properly?

A user can receive email but cannot send any. Which protocol, responsible for sending email, is potentially not configured properly?

• SNMP
• FTP
• POP3
• SMTP

EXPLANATION

The simple mail transfer protocol (SMTP) is probably not configured properly.
When troubleshooting, you need to confirm the SMTP setting because it is responsible for sending mail. POP3 receives mail, so wouldn't be responsible for the send issue, unless you are using Outlook (where POP3 authentication is required before email can be sent over SMTP). FTP sends files to remote computers and SNMP is used to manage networks.
FTP and SNMP are not responsible for users sending or receiving email.

SOURCE

http://searchexchange.techtarget.com/definition/SMTP

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Which of the following is true of IMAP?

Which of the following is true of IMAP?

• It uses port 110
• It sends and receives email
• It can only be used to send email
• It leaves messages on the mail server 

EXPLANATION

Unlike POP3, IMAP does not directly download and then remove messages from the mail server. Instead, it leaves the email on the server so that messages can be retrieved from various locations. IMAP is used only to retrieve email and uses port 143.
Here is some further discussion about this question

SOURCE

https://www.siteground.com/tutorials/email/pop3-imap-smtp-ports.htm

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All email services are based on which software model?

All email services are based on which software model?

• SMTP
• Client/server
• POP3
• TCP 

 

EXPLANATION

The client–server model of computing is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. A server host runs one or more server programs which share their resources with clients. A client does not share any of its resources, but requests a server's content or service function. Clients therefore initiate communication sessions with servers which await incoming requests.
Examples of computer applications that use the client–server model are email, network printing, and the web.

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What is the default port used by a POP3 server for communicating with a POP3 client?

What is the default port used by a POP3 server for communicating with a POP3 client?

• 587
• 110
• 109
• 25 

 

EXPLANATION

Port 110 is the default POP3 non-encrypted port.
Port 995 is the default POP3 port for encrypted (SSL) traffic.

SOURCE

http://quiz.techlanda.com/2017/12/what-is-default-port-used-by-pop3.html

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What is the default port used by a POP3 server for communicating with a POP3 client?

What is the default port used by a POP3 server for communicating with a POP3 client?

• 25
• 110
• 587
• 109 

 

EXPLANATION

Port 110 is the default POP3 non-encrypted port.
Port 995 is the default POP3 port for encrypted (SSL) traffic.

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In order to SEND email reliably, a mailserver MUST meet the following DNS requirement:

In order to SEND email reliably, a mailserver MUST meet the following DNS requirement:

• SPF and DKIM records
• A valid MX record
• A PTR record which matches the email domain
• A valid PTR record 

 

EXPLANATION

A sending mailserver shall have a valid PTR (reverse DNS lookup) record for its public IP address. That is, the PTR record must return the same IP address if submitted to a DNS lookup. If this is not the case, the recipient is likely to reject the mail as possible spam. (If IPv6 is used this also applies here, a point often overlooked)

MX records determine which computers accept inbound mail for

SOURCE

https://www.studiocoast.com.au/knowledgebase/194/email/support.aspx

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Which of the following does a DNS MX record provide for a given domain?

Which of the following does a DNS MX record provide for a given domain?

• The name of the inbound email server for that domain
• The web server details of the domain
• Outgoing email server for the domain
• Microsoft Exchange related information for the domain 

 

EXPLANATION

Mail eXchanger (MX) records specify a mail server responsible for accepting email messages on behalf of a recipient's domain,
and a preference value used to prioritize mail delivery if multiple mail servers are available. The set of MX records of a domain name specifies how email should be routed with the Simple Mail Transfer Protocol (SMTP).

SOURCE

https://en.wikipedia.org/wiki/MX_record

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When it comes to email, what is Postfix?

When it comes to email, what is Postfix?

• A mail user agent
• Paid software
• A mail submission agent
• A mail transfer agent 

 

EXPLANATION

Postfix is a mail transfer agent (MTA), which handle the long-haul delivery of the mail to other MTAs. Postfix supports LDAP, SMTP AUTH (SASL), TLS, and running in a chroot environment.
 

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Which of the following is NOT a daemon in Postfix?

Which of the following is NOT a daemon in Postfix?

• smtpd
• master
• qmgr   
• crond 

 

EXPLANATION

The crond daemon is a Linux daemon, not a Postfix daemon.
The master daemon is the brain of the Postfix mail system. It spawns all other daemons. The smtpd daemon (server) handles incoming connections. The qmgr daemon is the heart of the Postfix mail system. It processes and controls all messages in the mail queues.

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Which of the following is NOT a feature of the Microsoft Exchange 2016 Transport Pipeline?

Which of the following is NOT a feature of the Microsoft Exchange 2016 Transport Pipeline?

• Transport service
• Mailbox transport
• Back end transport service
• Front end transport service 

 

EXPLANATION

The Microsoft Exchange Transport Pipeline uses the following services:

• Front end transport service, which does basic message filtering based on domains, connectors, senders and recipients. It only connects with the transport service on a mailbox server and does not backlog any messages locally
• Transport service, which runs on all mailbox servers, and handles SMTP mail flow. It helps in message categorization and content inspection. The transport services routes messages between the Mailbox Transport service, the Transport Service and Front End Transport service.  This service does not queue messages locally
• Mailbox Transport, which handles receiving and sending SMTP to the transport service from the mailbox using remote procedures calls (RPCs).

SOURCE

https://technet.microsoft.com/en-us/library/aa996349(v=exchg.160).aspx

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