Node: Up and Running

Chapter 5. Helper APIs

This chapter covers a number of APIs that you’ll almost certainly use regularly but aren’t used as much as those discussed in Chapter 4.

DNS

Programmers, like end users, normally want to refer to things by their domain names instead of their IP addresses. The DNS module provides this lookup facility to you, but it is also used under the hood whenever you are able to use a domain name—for example, in HTTP clients.

The dns module consists of two main methods and a number of convenience methods. The two main methods are resolve(), which turns a domain name into a DNS record, and reverse(), which turns an IP address into a domain. All of the other methods in the dns module are more specialized forms of these methods.

dns.resolve() takes three arguments:

A string containing the domain to be resolved

This can include subdomains, such as www.yahoo.com. The www is technically a hostname, but the system will resolve it for you.

A string containing the types of records being requested

This requires a little more understanding of DNS. Most people are familiar with the “address” or A record type. This type of record maps an IPv4 domain to a domain name (as defined in the previous item). The “canonical name,” or CNAME, records allow you to create an alias of an A record or another CNAME. For example, www.example.com might be a CNAME of the A record at example.com. MX records point to the mail server for a domain for the use of SMTP. When you email [e-mail], the MX record ...