# dns/reverse Reverse-resolve an IP literal to a hostname (`getnameinfo`). ## Syntax 
[dns/reverse $addr ?$opts]
## Parameters - `$addr` — an IPv4 or IPv6 literal (string). Hostnames are rejected - `$opts` — optional option map: - `:numeric true` — format the literal instead of performing a PTR lookup (never touches the network) ## Examples 
[dns/reverse "8.8.8.8"]
# => "dns.google"

[dns/reverse "127.0.0.1" %{ :numeric true }]
# => "127.0.0.1"

[dns/reverse "::1" %{ :numeric true }]
# => "::1"
## Returns Hostname string, or `%Err{:message}` (including when the address has no PTR record — the lookup uses `NI_NAMEREQD`). ## See Also `dns/lookup`, `dns/parse`, `dns/ip?`
← dns/parse
dns/servers →