Comcast / Xfinity DNS Servers: Full List & Setup Guide (2026)

What Are Comcast / Xfinity DNS Servers?

Comcast and Xfinity DNS servers are the Domain Name System resolvers operated by Comcast that translate domain names like google.com into the IP addresses your device connects to. Every website you open on an Xfinity connection sends a DNS query to these servers first.

When you activate Xfinity Internet, your gateway is automatically configured to use Comcast's own DNS servers. They handle resolution for over 30 million broadband customers across the United States and are generally reliable — but independent benchmarks consistently show public resolvers like Cloudflare and Google answering queries 50–80% faster than most ISP DNS, Comcast included.

You can measure this for yourself in seconds with DNS Robot's DNS Speed Test — it benchmarks the major public resolvers from your own network and shows which is fastest where you are.

Comcast / Xfinity DNS Server IP Addresses (IPv4)

Here are Comcast's default DNS server addresses, assigned automatically to Xfinity residential Internet customers nationwide.

The 75.75.75.75 / 75.75.76.76 pair (easy to remember, sometimes nicknamed "75-75-75-75") is Comcast's primary public resolver set and is used by Xfinity customers in every region.

These addresses are anycast, so the physical server you reach depends on your location. You can confirm they are currently responding with DNS Robot's DNS Lookup tool.

Xfinity IPv6 DNS Servers

Comcast has one of the largest IPv6 deployments of any U.S. ISP, and IPv6 is enabled by default on most Xfinity gateways. Here are the Comcast IPv6 DNS resolver addresses.

If you switch to a third-party DNS provider, update both your IPv4 and IPv6 DNS settings. Leaving IPv6 on Comcast's defaults while changing only IPv4 causes split behavior — some lookups still route through Comcast's servers, which can mask the speed and privacy gains you were after.

Comcast Business DNS Servers

Comcast Business customers use the same 75.75.75.75 / 75.75.76.76 DNS infrastructure by default. Business accounts can also order static IP addresses and run their own resolvers for custom domain and mail configurations.

If you run a business on Comcast, consider a security-focused public resolver such as Quad9 (9.9.9.9) or Cloudflare for Teams. These filter known malicious domains at the DNS layer, adding protection without installing anything on each device.

Why Change Xfinity's Default DNS?

Comcast's DNS works fine for everyday browsing, but there are solid reasons to switch to a public resolver.

• Faster resolution — Cloudflare (~11ms average) and Google (~22ms) typically beat ISP DNS. Comcast latency commonly sits in the 30–50ms range depending on region and time of day

• Better uptime — Public resolvers run global anycast networks with 99.99%+ availability. ISP DNS outages, when they happen, can take a whole region offline

• Privacy — Public resolvers like Cloudflare commit to not logging queries and undergo third-party audits. ISP DNS data handling is governed by Comcast's broader privacy policy

• No NXDOMAIN redirection — Some ISPs have historically redirected mistyped/unknown domains to a branded search page. Switching DNS guarantees you get a clean NXDOMAIN instead

• Built-in security — Quad9 (9.9.9.9) blocks known malware and phishing domains; Cloudflare for Families (1.1.1.3) blocks malware and adult content at the DNS level

• Encryption support — Public resolvers support DNS-over-HTTPS and DNS-over-TLS, so your lookups can't be read or modified on the network

Best DNS Servers for Xfinity Users

These are the best public DNS alternatives for Comcast/Xfinity customers, ranked by speed, privacy and features. All are free and work with any Xfinity plan.

For most Xfinity users, Cloudflare (1.1.1.1) is the best overall pick — fastest globally with the strongest privacy stance. Want malware filtering? Quad9 (9.9.9.9). Want a cleaner, ad-light network? AdGuard DNS.

Don't guess which is fastest for you — the closest resolver depends on your city and Comcast region. Run DNS Robot's free DNS Speed Test to benchmark Cloudflare, Google and Quad9 from your own connection and pick the real winner.

How to Change DNS on an Xfinity Gateway

This is where Xfinity differs from most ISPs: the xFi Gateway (XB6, XB7, XB8 and similar) usually locks the DNS field, so you often cannot set a custom DNS server directly on a Comcast-issued gateway in router mode. Below are the three real-world paths, from easiest to most thorough.

Method 1: Try the xFi App / Admin Tool

First, check whether your gateway exposes a DNS setting at all — a minority of firmware versions and customer-owned modems do.

• Step 1 — Open a browser and go to 10.0.0.1 (the Xfinity gateway admin address). Sign in — the default is usually admin / password unless you changed it

• Step 2 — Go to Gateway → Connection → Local IP Network (labels vary by model)

• Step 3 — Look for a DNS or DHCP DNS field. If it's editable, enter your preferred servers (e.g. 1.1.1.1 and 1.0.0.1) and Save Settings

• Step 4 — If the field is greyed out or missing, your gateway is locked — use Method 2 (per-device) or Method 3 (Bridge Mode) instead

Method 2: Set DNS Per Device (works on any gateway)

Because the gateway often locks DNS, the most reliable approach is to set DNS on each device. It takes a minute per device and overrides whatever the gateway hands out. Jump to the Windows, Mac or mobile steps below.

Method 3: Bridge Mode + Your Own Router

For full, network-wide control, put the Xfinity gateway into Bridge Mode and connect your own router (TP-Link, ASUS, Netgear, eero). Your router then handles DHCP and DNS, so you can set any resolver once for every device.

• Step 1 — Sign in at 10.0.0.1, go to Gateway → At a Glance, and enable Bridge Mode (this disables the gateway's Wi-Fi and routing)

• Step 2 — Connect your own router's WAN port to the gateway and set it up normally

• Step 3 — In your router's settings, set the WAN/DHCP DNS to your chosen servers (e.g. 1.1.1.1 / 1.0.0.1)

• Step 4 — Reboot and confirm devices are using the new DNS with the verification steps below

Change DNS on Windows (Xfinity Connection)

Setting DNS on Windows overrides the gateway's DNS for that PC. Here's how on Windows 11 and 10.

• Step 1 — Open Settings → Network & Internet → click your connection (Wi-Fi or Ethernet)

• Step 2 — Click Edit next to DNS server assignment

• Step 3 — Switch from Automatic (DHCP) to Manual, then turn on IPv4

• Step 4 — Preferred DNS = 1.1.1.1, Alternate DNS = 1.0.0.1 (Cloudflare)

• Step 5 — (Optional) Turn on IPv6 and add 2606:4700:4700::1111 / 2606:4700:4700::1001, then Save

# PowerShell: set DNS on the active adapter
$adapter = Get-NetAdapter | Where-Object {$_.Status -eq 'Up'} | Select-Object -First 1
Set-DnsClientServerAddress -InterfaceIndex $adapter.ifIndex -ServerAddresses '1.1.1.1','1.0.0.1'

# Flush the resolver cache and verify
Clear-DnsClientCache
Get-DnsClientServerAddress -InterfaceIndex $adapter.ifIndex

Change DNS on Mac (Xfinity Connection)

macOS lets you override DNS per network service in a few clicks.

• Step 1 — Open System Settings → Network → select your active connection (Wi-Fi or Ethernet)

• Step 2 — Click Details → choose DNS from the sidebar

• Step 3 — Click + and add 1.1.1.1 and 1.0.0.1

• Step 4 — Remove any existing Comcast DNS entries (75.75.75.75) with −

• Step 5 — Click OK → Apply

# Terminal: set DNS for the Wi-Fi service
networksetup -setdnsservers Wi-Fi 1.1.1.1 1.0.0.1

# Flush the DNS cache
sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

# Verify and test resolution
networksetup -getdnsservers Wi-Fi
dig @1.1.1.1 google.com +short

Change DNS on iPhone & Android (Xfinity Wi-Fi)

If the gateway locks DNS, override it on your phone instead.

iPhone / iPad

• Step 1 — Settings → Wi-Fi → tap the (i) next to your Xfinity network

• Step 2 — Scroll to Configure DNS → switch from Automatic to Manual

• Step 3 — Delete existing entries, then Add Server → 1.1.1.1 and 1.0.0.1

• Step 4 — Tap Save

Android (Private DNS)

Android 9+ has a global Private DNS feature that applies encrypted DNS everywhere — including Xfinity Wi-Fi and mobile data.

• Step 1 — Settings → Network & Internet → Private DNS

• Step 2 — Select Private DNS provider hostname

• Step 3 — Enter one.one.one.one (Cloudflare) or dns.google (Google)

• Step 4 — Tap Save

How to Verify Your DNS Changed

After changing DNS, confirm your device is actually using the new servers.

# Windows — show the resolver in use
nslookup google.com
# The "Server:" line should show 1.1.1.1, not 75.75.75.75

# Mac/Linux — compare response times
dig google.com @1.1.1.1 | grep "Query time"     # Cloudflare (~10-20ms)
dig google.com @75.75.75.75 | grep "Query time" # Comcast (compare)

For a visual, side-by-side comparison from your own browser, run DNS Robot's DNS Speed Test — it ranks the major resolvers by real latency so you can confirm the one you picked is actually faster than Comcast's.

If nslookup still shows 75.75.75.75, flush your DNS cache and restart your browser. Router-level changes can take 10–15 minutes to reach every device.

Common Xfinity DNS Issues & Fixes

Comcast DNS occasionally has slowdowns and outages. Here are the most common problems and how to solve them.

Comcast DNS Server Not Responding

Your browser shows "DNS server not responding" or DNS_PROBE_FINISHED_NXDOMAIN even though the modem shows a solid connection.

• Quick fix — Switch to Cloudflare (1.1.1.1) or Google (8.8.8.8) to bypass Comcast's resolvers entirely

• Restart the gateway — Unplug the Xfinity gateway for 30 seconds, then plug it back in and wait 2–3 minutes

• Flush DNS cache — ipconfig /flushdns on Windows or sudo dscacheutil -flushcache on Mac

• Check for an outage — Look at the Xfinity app status page or Downdetector Xfinity

Slow DNS Lookups on Xfinity

If sites pause before loading but then download quickly, slow DNS resolution is the likely cause. ISP resolvers can sit at 30–50ms versus ~11ms for Cloudflare, and a single page can fire 20–50 lookups.

Switching to a faster resolver shortens every lookup your device makes — pages, images, fonts, APIs and background calls all start sooner.

xFi Gateway Won't Let Me Change DNS

This is the most common Xfinity-specific complaint: the DNS field at 10.0.0.1 is greyed out or missing. It's a deliberate restriction on most xFi Gateways.

Your options when DNS is locked:

• Set DNS per device — Override on each computer, phone, console and TV (see the steps above). The fastest path for most people

• Use Bridge Mode + your own router — Full network-wide control over DNS and every other setting

• Android Private DNS — Forces encrypted DNS at the OS level regardless of the gateway

• Browser DoH — Chrome, Edge and Firefox can use DNS-over-HTTPS, bypassing the gateway's DNS for web traffic only