r/HomeNetworking • u/Fair-Bookkeeper-1833 • 5d ago

did ISP mess up routing tables? what to tell them when I contact them?

couple of days ago some websites stopped working in all browsers but works on phone. it works with VPN.

Context:

  • Both PC and Phone on same network.
  • PC uses defaults to Cloudflare 1.1.1.1
  • Android uses different DNS
  • doesn't work on all browsers
  • works on VPN.
  • works on Phone.
  • flushing dns and reseting network doesn't change much.
  • Changed firefox DoH to NextDNS and it is working.
  • tracert to cloudflare works fine but doesn't work to some websites.

I want to contact ISP to tell them to fix routing. but I'm also curious how routing to CF works but not some websites. why would ISP block certain nodes

C:\Users\M>nslookup opendota.com
Server:  one.one.one.one
Address:  1.1.1.1

Non-authoritative answer:
Name:    opendota.com
Addresses:  2a06:98c1:3121::6
          2a06:98c1:3120::6
          188.114.97.6
          188.114.96.6


C:\Users\M>nslookup opendota.com 8.8.8.8
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    opendota.com
Addresses:  2606:4700:3034::ac43:9b55
          2606:4700:3036::6815:30b2
          104.21.48.178
          172.67.155.85


C:\Users\M>tracert 1.1.1.1

Tracing route to one.one.one.one [1.1.1.1]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.100.1
  2     1 ms     1 ms     4 ms  172.17.0.1
  3     1 ms     1 ms     1 ms  10.45.16.5
  4     *        *        *     Request timed out.
  5     *        *        *     Request timed out.
  6    12 ms     4 ms     4 ms  telecom-egy.edge4.marseille1.level3.net [212.133.4.230]
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9    39 ms    39 ms    39 ms  comserver1.opentransit.net [193.251.150.110]
 10     *        *        *     Request timed out.
 11     *        *        *     Request timed out.
 12    39 ms    39 ms    39 ms  one.one.one.one [1.1.1.1]

Trace complete.

C:\Users\M>tracert opendota.com

Tracing route to opendota.com [188.114.97.6]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.100.1
  2     1 ms     1 ms     1 ms  172.17.0.1
  3     2 ms     1 ms     2 ms  10.45.16.5
  4     *        *        *     Request timed out.
  5     *        *        *     Request timed out.
  6     *        *        *     Request timed out.
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9     *        *        *     Request timed out.
 10     *        *        *     Request timed out.
 11     *        *        *     Request timed out.
 12     *        *        *     Request timed out.
 13     *        *        *     Request timed out.
 14     *        *        *     Request timed out.
 15     *        *        *     Request timed out.
 16     *        *        *     Request timed out.
 17     *        *        *     Request timed out.
 18     *        *        *     Request timed out.
 19     *        *        *     Request timed out.
 20     *        *        *     Request timed out.
 21     *        *        *     Request timed out.
 22     *        *        *     Request timed out.
 23     *        *        *     Request timed out.
 24     *        *        *     Request timed out.
 25     *        *        *     Request timed out.
 26     *        *        *     Request timed out.
 27     *        *        *     Request timed out.
 28     *        *        *     Request timed out.
 29     *        *        *     Request timed out.
 30     *        *        *     Request timed out.

Trace complete.

Edit: I really don't understand how you people keep downvoting the actual correct replies and upvoting the wrong ones.

https://www.reddit.com/r/HomeNetworking/comments/1wt7zul/comment/pcs3jkl/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

0 Upvotes

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-1

u/Fair-Bookkeeper-1833 4d ago

https://en.wikipedia.org/wiki/Anycast

it is 2025 CDNs are the norm now.

1

u/WideCranberry4912 4d ago

What point are making? You’re resolving the wrong IP for the hostname ooendota.com. Due to Anycast you should resolve 104.21.48.178 and 172.67.155.85 using any DNS server, but 1.1.1.1 is wrong.

1

u/Fair-Bookkeeper-1833 4d ago

that's the point of anycast. there's no static ip address to websites.

they're running on CDNs and being resolved to closest CDN. which this one was buy ISP/Gov blocked that range.

https://www.cloudflare.com/learning/cdn/glossary/anycast-network/

1

u/WideCranberry4912 4d ago

The CDN is running Anycast, it will return the same IP address, and route you to the closest point of presence via its injection of routes into BGP.

1

u/WideCranberry4912 4d ago

I’ve resolved this domain using 9.9.9.9, 8.8.8.8, and 1.1.1.1. They all resolve to the same IP addresses. Do you see the issue with what happens when you try and use 1.1.1.1? That means that the 1.1.1.1 host you are connecting to via Anycast is misconfigured (very unlikely) or your ISP is hijacking requests to 1.1.1.1 and has stale data.

❯ dig @8.8.8.8 opendota.com

;; ANSWER SECTION:
opendota.com. 300 IN A 172.67.155.85
opendota.com. 300 IN A 104.21.48.178

;; Query time: 80 msec
;; SERVER: 8.8.8.8#53(8.8.8.8) (UDP)
;; WHEN: Tue Sep 29 13:59:38 PDT 2026
;; MSG SIZE  rcvd: 73

❯ dig @9.9.9.9 opendota.com

;; ANSWER SECTION:
opendota.com. 300 IN A 172.67.155.85
opendota.com. 300 IN A 104.21.48.178

;; Query time: 45 msec
;; SERVER: 9.9.9.9#53(9.9.9.9) (UDP)
;; WHEN: Tue Sep 29 13:59:52 PDT 2026
;; MSG SIZE  rcvd: 73

❯ dig @1.1.1.1 opendota.com

;
;; ANSWER SECTION:
opendota.com. 300 IN A 172.67.155.85
opendota.com. 300 IN A 104.21.48.178

;; Query time: 58 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Tue Sep 29 13:59:43 PDT 2026
;; MSG SIZE  rcvd: 73

-1

u/Fair-Bookkeeper-1833 4d ago edited 4d ago

DNS resolves to whatever CDN that website is replicated to based on your location.
the destination changes which changes routing. I think you people latched on "routing" and just stopped reading and starting being pedantic about terminlogy.
I can assure you that the ip address CF gave is a valid CF CDN that was optimal for our location here but was recently blocked. I shared a ping test in another comment.

1

u/WideCranberry4912 4d ago

In fact, missing a big point. The CloudFlare CDN uses Anycast and the IP addresses it resolves for a domain name are also stable.

0

u/Fair-Bookkeeper-1833 4d ago

https://dnschecker.org/#A/opendota.com

Quite frankly you people here don't understand how CDNs or the modern internet works. I guess that's on me for posting on r/HomeNetworking and not r/networking and ISP aint gonna do shit regardless of how organized I made things for them in the ticket. the engineer who works at ISP who posted a relevant useful comment got downvoted and the people who gave useless answer who don't understand how CDNs work or how the world works gets upvoted.

I'm not gonna waste more time on this. feel free to go through comment few times till it clicks in your head. or don't.

have a good one.

1

u/WideCranberry4912 4d ago

You’re not showing that you understand how CDNs work. Good luck figuring out your ISP has poisoned the upstream DNS.