nslookup function

Lookup a hostname

The nslookup function is similar to nsl but works on all platforms and can resolve ipv6 addresses if supported by the OS. Default behavior raises an error if lookup fails.

nslookup(host, ipv4_only = FALSE, multiple = FALSE, error = TRUE)

has_internet()

Arguments

• host: a string with a hostname
• ipv4_only: always return ipv4 address. Set to FALSE to allow for ipv6 as well.
• multiple: returns multiple ip addresses if possible
• error: raise an error for failed DNS lookup. Otherwise returns NULL.

Details

The has_internet function tests for internet connectivity by performing a dns lookup. If a proxy server is detected, it will also check for connectivity by connecting via the proxy.

Examples

# Should always work if we are online
nslookup("www.r-project.org")

# If your OS supports IPv6
nslookup("ipv6.test-ipv6.com", ipv4_only = FALSE, error = FALSE)