English
Menu

Network Design and Operations

Which DNS resource record specifies the mail server that receives email addressed to a domain?

  1. ACNAME
  2. BNS
  3. CMX
Show answer and explanation

Answer: C. MX

An MX record gives the server that mail for a domain is delivered to, as in "mail for example.com is received by mail.example.com." Several servers can be registered with preference values, and delivery is tried starting with the server with the lowest value. A CNAME record defines an alias, used for example to make www.example.com an alias of web.example.net. NS gives the domain's authoritative DNS servers, and A and AAAA give IPv4 and IPv6 addresses, respectively.

  • A. A CNAME record registers one name as an alias of another name.
  • B. An NS record gives the authoritative DNS servers that hold the domain's information.
  • C. Correct. An MX record gives the server that mail is delivered to.
Practice this topic Back to topic

Related calculators

IP address and subnet calculatorFind the network and broadcast addresses, host range and host count from an IP address and a prefix or mask, with a binary view and subnet splittingDijkstra's algorithm calculatorCompute shortest paths and distances from a list of weighted edges, and follow each step of finalizing vertices in a table and a diagram

Books on Network Design and Operations Ad

As an Amazon Associate I earn from qualifying purchases.

More Network Design and Operations questions

  1. Which statement correctly describes how recursive and non-recursive (iterative) queries are used in DNS name resolution?
  2. For a web server move, the IP address in the A record for www.example.com will be changed. The record's TTL is currently 86400 seconds, and to keep the time the old address is used after the change to about 5 minutes at most, the TTL will be lowered to 300 seconds beforehand. Resolvers cache records exactly for their TTL. Which is the correct deadline for lowering the TTL?
  3. A router that performs NAPT (outside address 198.51.100.7) is configured with port forwarding, a static setting that translates only the destination: "forward traffic arriving at outside TCP port 8080 to port 80 on the inside web server 192.168.1.20." When host 203.0.113.9 on the internet connects from source port 51000 to port 8080 on 198.51.100.7, which is the destination and source of the packets the web server receives?
  4. An ACL that checks incoming packets from the top is applied to a router interface. Rule 1 is "permit traffic to TCP port 443 on 10.0.0.10," rule 2 is "deny all traffic from source 192.168.1.0/24," and rule 3 is "permit traffic from source 192.168.0.0/16 to TCP port 80"; there are no other rules. Of the four packets (i) "from 192.168.1.5 to TCP port 443 on 10.0.0.10," (ii) "from 192.168.1.5 to TCP port 80 on 10.0.0.20," (iii) "from 192.168.2.5 to TCP port 80 on 10.0.0.20" and (iv) "from 192.168.2.5 to TCP port 22 on 10.0.0.20," which choice lists all the packets that are let through?
  5. In IPv6, which range holds link-local addresses, which are used only within the same link and are always configured automatically on every interface that uses IPv6?

Comparisons in this topic