Skip to main content
Deno provides comprehensive networking capabilities including TCP/UDP connections, TLS support, and DNS resolution.

​
DNS Resolution

​
Deno.resolveDns()

Performs DNS resolution against the given query, returning resolved records. 
function resolveDns(
  query: string,
  recordType: RecordType,
  options?: ResolveDnsOptions
): Promise<string[] | Record[]>
​
query
string
required
The domain name to resolve
​
recordType
RecordType
required
The type of DNS record to query. Supported types: "A", "AAAA", "ANAME", "CAA", "CNAME", "MX", "NAPTR", "NS", "PTR", "SOA", "SRV", "TXT"
​
options.nameServer
object
The name server to use for lookups. Defaults to system configuration.
​
options.nameServer.ipAddr
string
The IP address of the name server
​
options.nameServer.port
number
default:"53"
The port number the query will be sent to
​
options.signal
AbortSignal
An abort signal to allow cancellation of the DNS resolution operation
Example: 
// Query A records
const a = await Deno.resolveDns("example.com", "A");
console.log(a); // ["93.184.216.34"]

// Query AAAA records with custom name server
const aaaa = await Deno.resolveDns("example.com", "AAAA", {
  nameServer: { ipAddr: "8.8.8.8", port: 53 },
});

// Query MX records
const mx = await Deno.resolveDns("example.com", "MX");
console.log(mx); // [{ preference: 10, exchange: "mail.example.com" }]
Requires allow-net permission.

​
Network Interfaces

​
Deno.networkInterfaces()

Returns an array of the network interface information. 
function networkInterfaces(): NetworkInterfaceInfo[]
​
name
string
The network interface name
​
family
'IPv4' | 'IPv6'
The IP protocol version
​
address
string
The IP address bound to the interface
​
netmask
string
The netmask applied to the interface
​
scopeid
number | null
The IPv6 scope id or null
​
cidr
string
The CIDR range
​
mac
string
The MAC address
Example: 
const interfaces = Deno.networkInterfaces();
console.log(interfaces);
// [
//   {
//     name: "en0",
//     family: "IPv4",
//     address: "192.168.1.100",
//     netmask: "255.255.255.0",
//     scopeid: null,
//     cidr: "192.168.1.100/24",
//     mac: "00:11:22:33:44:55"
//   }
// ]
Requires allow-sys permission.

​
Address Types

Deno supports multiple address types for network connections:

​
NetAddr

Represents a TCP or UDP network address. 
interface NetAddr {
  transport: "tcp" | "udp";
  hostname: string;
  port: number;
}

​
UnixAddr

Represents a Unix domain socket address. 
interface UnixAddr {
  transport: "unix" | "unixpacket";
  path: string;
}

​
VsockAddr

Represents a VSOCK address for VM communication. 
interface VsockAddr {
  transport: "vsock";
  cid: number;
  port: number;
}

​
Working with Network Addresses

// TCP address
const tcpAddr: Deno.NetAddr = {
  transport: "tcp",
  hostname: "127.0.0.1",
  port: 8080
};

// Unix domain socket
const unixAddr: Deno.UnixAddr = {
  transport: "unix",
  path: "/tmp/my.sock"
};

// VSOCK address (for VM communication)
const vsockAddr: Deno.VsockAddr = {
  transport: "vsock",
  cid: 3,
  port: 1234
};

​
DNS Record Types

​
A and AAAA Records

const ipv4 = await Deno.resolveDns("example.com", "A");
// Returns: string[] - IPv4 addresses

const ipv6 = await Deno.resolveDns("example.com", "AAAA");
// Returns: string[] - IPv6 addresses

​
MX Records

interface MxRecord {
  preference: number;
  exchange: string;
}

const mx = await Deno.resolveDns("example.com", "MX");
// Returns: MxRecord[]

​
SRV Records

interface SrvRecord {
  priority: number;
  weight: number;
  port: number;
  target: string;
}

const srv = await Deno.resolveDns("_http._tcp.example.com", "SRV");
// Returns: SrvRecord[]

​
CAA Records

interface CaaRecord {
  critical: boolean;
  tag: string;
  value: string;
}

const caa = await Deno.resolveDns("example.com", "CAA");
// Returns: CaaRecord[]

​
SOA Records

interface SoaRecord {
  mname: string;
  rname: string;
  serial: number;
  refresh: number;
  retry: number;
  expire: number;
  minimum: number;
}

const soa = await Deno.resolveDns("example.com", "SOA");
// Returns: SoaRecord[]

​
TXT Records

const txt = await Deno.resolveDns("example.com", "TXT");
// Returns: string[][] - Array of text record arrays

​
Error Handling

Network operations can fail for various reasons. Always handle errors appropriately: 
try {
  const records = await Deno.resolveDns("nonexistent.invalid", "A");
} catch (error) {
  if (error instanceof Deno.errors.NotFound) {
    console.error("Domain not found");
  } else if (error instanceof Deno.errors.TimedOut) {
    console.error("DNS query timed out");
  } else {
    console.error("DNS resolution failed:", error);
  }
}

​
Canceling Operations

Use AbortSignal to cancel network operations: 
const controller = new AbortController();
const { signal } = controller;

// Cancel after 5 seconds
setTimeout(() => controller.abort(), 5000);

try {
  const records = await Deno.resolveDns("example.com", "A", { signal });
  console.log(records);
} catch (error) {
  if (error.name === "AbortError") {
    console.log("DNS query was cancelled");
  }
}

​
Permissions

Network operations require the --allow-net permission: 
# Allow all network access
deno run --allow-net script.ts

# Allow access to specific hosts
deno run --allow-net=example.com,api.github.com script.ts

# System info requires allow-sys
deno run --allow-sys script.ts

Build docs developers (and LLMs) love

Get started for freeTalk to us