10
votes
Accepted
How are IPv4 Addresses provided uniquely to domains?
Who mainly provides IP addresses to domains? As in, who commands, "www.google.com, 103.233.38.93 is yours; www.stackexchange.com I will assign 104.16.115.182 to you; etc."
Normally IP addresses are ...
- 13.3k
8
votes
Why is DNS an application layer protocol?
Protocols at the Physical, Data-Link, Network, or Transport layers do not use names. Only applications need to use names, so DNS is an application-layer protocol because it allows the application to ...
- 99.6k
8
votes
Accepted
Why is DNS an application layer protocol?
DNS is a application layer protocol, because DNS query and answer is the application level communications. Application layer only understand the query and answer section in the DNS packet.
so ...
- 388
7
votes
Accepted
What is IP-over-DNS tunnelling?
Ron is right with his comment.
IP-over-DNS tunneling (or more common name DNS tunneling) is a kind of attack, that allows to bypass usual network protection and send/receive data over DNS protocol, ...
- 344
6
votes
Can I see what happens when I run a DNS query?
As others have already answered, most usually a host sends a recursive query to a nominated resolver, often a local server or router, often belonging to an ISP or Google's well-known (distributed) 8.8....
- 16.2k
5
votes
Why is DNS an application layer protocol?
I think that DNS is an application layer protocol because if for
example i want to create a TCP connection i need the destination ip
address in layer 4, Am i correct?
IP is a layer 3 protocol.
...
- 1,614
5
votes
It's not showing the DNS why it is called reverse IP lookup?
Reverse DNS is a term for looking up the DNS PTR record for an IP address - essentially resolving it 'backwards' to a host name (in contrast to 'forward' resolving a host name to an IP address using ...
- 84.4k
5
votes
Accepted
What are some high-traffic websites that operate with a global anycast IP address?
A couple of examples are:
api.twitter.com
one.one.one.one
dns.google
There are always exceptions however - you'll notice that within China, the IP for say api.twitter.com is different for reasons ...
- 9,431
5
votes
What's the meaning of requests in Load-balancer?
That seems to use the term 'request' both for DNS queries and for HTTP requests, which makes it a bit confusing. Most load balancers however are able to balance all kinds of application protocols, ...
- 17.4k
4
votes
How are packets routed based on IP and how are those routes acquired?
Routers learn about routes in three ways:
Directly connected networks
Manually configured static routes
Dynamically through routing protocols
A router, receiving a packet on an interface will look ...
- 99.6k
4
votes
Accepted
Nameserver availability within single ASN
Multi-ASN in this case is more of a proxy for a high degree of network resilience. The basic idea is that primary and secondary servers should be deployed in such a way that the loss of even multiple ...
- 6,114
4
votes
Can I see what happens when I run a DNS query?
A normal DNS client just queries the (DHCP or statically) assigned DNS servers. Only DNS servers usually query root servers, doing a recursive query.
You can use a packet capture of your choice and ...
- 84.4k
4
votes
Accepted
How do I find the IP of the DNS server that respond for a specific domain name?
The authoritative name server should be in the domain's NS record.
In Windows, this can be looked up
nslookup -type=ns somedomain.com
In Linux, something like
dig somedomain.com NS +noall +answer
...
- 84.4k
4
votes
Accepted
If you have multiple domains pointing to the same IP address, can you see which domain a packet was sent to?
Application-layer protocols such as HTTP generally have this capability.
At the network layer, no, you can't tell.
- 5,469
4
votes
Accepted
Why DNS services Like google public DNS and Cloudflare 1.1.1.1 has ipv6 versions?
The plan for IPv6 is to ultimately replace IPv4 in entirety. In the long run, it doesn't make sense to run two full stacks in parallel.
Also, some providers serve their clients using IPv4 private ...
- 84.4k
4
votes
Accepted
What does 'CPE' stand for, and what is it?
CPE usually stands for customer premises equipment - a router or modem that is supplied by a provider. The opposite is central office equipment COE.
A CPE ID is used to uniquely identify a customer-...
- 84.4k
3
votes
Accepted
Router decision making w.r.t web browsers
You're mixing up various layers of the Internet Protocol Suite (or OSI model if you like). Routers do not interact with browers directly. Routers interact with hosts, which have IP addresses. As far ...
- 17.4k
3
votes
Accepted
Host IPv6-only website and allow access to IPv4-only clients
IPv4 and IPv6 are separate protocols. So if you want IPv4 only clients to be able to access your IPv6 only server you will need some kind of gateway/proxy service that can provide an IPv4 address to ...
- 13.3k
3
votes
How WANs work and why it is it bad to run DNS and DHCP on a router?
WAN is a very subjective term. Routers have interfaces. Some types of router interfaces are more likely to be used as or called WAN interfaces. For example, PPP, HDLC, Frame relay, etc. are rarely ...
- 99.6k
3
votes
Connecting to remote device via hostname that gets its IP from DHCP
If your DHCP and DNS servers both implement DDNS (that's Dynamic [updates] to DNS, I know ISC's Open Source servers do this, and I'm sure there are several others), you can have the DHCP server update ...
- 356
3
votes
How do you check glue records if your ISP blocks access to the root servers?
Change your ISP. Blocking access to root DNS servers with "DoS prevention" is not something a serious ISP would practice (unless you live in a country with government regulations in place).
...
- 404
3
votes
Accepted
Only DNS filter guest wireless network, but not main wireless network running through same port on switch
I assume you are using OpenDNS' web filtering functionality here, and it looks like that essentially involves using their DNS servers to handle lookups, rather than your own.
You could define two ...
- 2,449
3
votes
Accepted
Who generates all the DNS requests when I plug my public IP router to the network?
Many (really, really many) bots scan all Internet public IP all time, and try to exploit any weakness found in many way.
Specifically, DNS is often used to perform DDOS attack by amplification, see ...
- 19.6k
3
votes
Accepted
Why only 13 adresses for the DNS root zone
"Each IPv4 address" meaning "each IPv4 DNS root server entry". The article is quite clear on this. 512 bytes of (minimum) UDP payload divided by 32 bytes equals 16. They left 96 bytes for future ...
- 84.4k
3
votes
Accepted
How does a DNS response reach a client behind a NAT?
The type of translation you are referring to is a Dynamic PAT. This type of translation is often unidirectional. Which is to say, traffic only flows in the outbound direction. But a more accurate way ...
- 15k
3
votes
Accepted
Cisco IOS: DNS Servers via DHCP
There are some options the client can request when IOS XE (and vanilla IOS, too) is a DHCP client.
I dont' have a Catalyst 9k at hand to test, but some of it might be in there, too
This is from a ...
- 8,836
3
votes
Able to ping Domain internal address on home network, why?
You are pinging to public resolve name. Therefore you are getting reply. You cannot ping directly to internal network. If you are getting reply from unexpected Ip address there will be many reasons.
...
- 3,118
3
votes
How do machines setup a route in a network?
How does my computer and x.x.x.x know how to talk to each other? If I
use a human messengers analogy, I would tell a person to go get me a
package, and I would give him the address of the location and ...
- 99.6k
3
votes
Why do we need DNS?
You can do calculations on IP addresses, not on domain names. This allows you to do subnetting, aggregation, route comparison, and many more things.
These functions are needed to do route selection, ...
- 17.4k
2
votes
Copying bytes from Wireshark
TCPReplay can be used to replay UDP traffic from a filtered and exported packet capure. Note that it will not work with multiple TCP streams due to issues with the sequence numbers.
You may also be ...
- 309
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